10 - Dominica 72,500
Dominica, (French: Dominique)  officially the Commonwealth of Dominica, is an island nation in the  Caribbean Sea. To the north-northwest lies Guadeloupe, to the southeast  Martinique. Its size is 754 square kilometres (291 sq mi) and the  highest point in the country is Morne Diablotins, which has an elevation  of 1,447 metres (4,750 ft). The Commonwealth of Dominica has an  estimated population of 72,500. The capital is Roseau.

Dominica has been nicknamed the  "Nature Isle of the Caribbean" for its seemingly unspoiled natural  beauty. It is the youngest island in the Lesser Antilles, still being  formed by geothermal-volcanic activity, as evidenced by the world's  second-largest boiling lake. The island features lush mountainous  rainforests, home of many rare plant, animal and bird species. There are  xeric areas in some of the western coastal regions, but heavy rainfall  can be expected inland. The Sisserou Parrot (also known as the Imperial  Amazon), the island's national bird, is featured on the national flag.  Dominica's economy is heavily dependent on both tourism and agriculture.  More images after the break...
Christopher Columbus named the island after the day  of the week on which he spotted it, a Sunday (dominica in Latin),  November 3, 1493. In the next hundred years after Columbus' landing,  Dominica remained isolated, and even more Caribs settled there after  being driven from surrounding islands as European powers entered the  region. France formally ceded possession of Dominica to the United  Kingdom in 1763. The United Kingdom then set up a government and made  the island a colony in 1805.
The emancipation of African  slaves occurred throughout the British Empire in 1834, and, in 1838,  Dominica became the first British Caribbean colony to have a legislature  controlled by an African majority. In 1896, the United Kingdom  reassumed governmental control of Dominica, turning it into a Crown  colony. Half a century later, from 1958 to 1962, Dominica became a  province of the short-lived West Indies Federation. In 1978, Dominica  became an independent nation. 
Link09 The Marshall Islands 62,000 
The Marshall Islands  en-us-Marshall Islands.ogg, officially the Republic of the Marshall  Islands (RMI), is a Micronesian nation of atolls and islands in the  middle of the Pacific Ocean, just west of the International Date Line  and just north of the Equator. This nation of roughly 62,000 people is  located north of Nauru and Kiribati, east of the Federated States of  Micronesia, and south of the U.S. territory of Wake Island, to which it  lays claim. 
Link08 Saint Kitts and Nevis 52,000
The Federation of Saint Kitts and Nevis (also known as the Federation of  Saint Christopher and Nevis),[2] located in the Leeward Islands, is a  federal two-island nation in the West Indies. It is the smallest  sovereign nation in the Americas, in both area and population.
The capital city and  headquarters of government for the federated state is Basseterre on the  larger island of Saint Kitts. The smaller state of Nevis lies about 2  miles (3 km) southeast of Saint Kitts, across a shallow channel called  "The Narrows".
Historically, the British  dependency of Anguilla was also a part of this union, which was then  known collectively as Saint Christopher-Nevis-Anguilla. Saint Kitts and  Nevis are geographically part of the Leeward Islands. To the  north-northwest lie the islands of Saint Eustatius, Saba, Saint  Barthélemy, and Saint-Martin/Sint Maarten. To the east and northeast are  Antigua and Barbuda, and to the southeast is the small uninhabited  island of Redonda, and the island of Montserrat, which currently has an  active volcano (see Soufrière Hills).
Saint Kitts and Nevis were  amongst the first islands in the Caribbean to be settled by Europeans.  Saint Kitts was home to the first British and French colonies in the  Caribbean. 
Link07 Liechtenstein 35,000
The Principality of Liechtenstein  German: Fürstentum Liechtenstein,  correct-German-pronunciation-of-Fuerstentum-Liechtenstein.ogg is a  doubly landlocked alpine microstate in Western Europe, bordered by  Switzerland to the west and south and by Austria to the east. Its area  is just over 160 km² (about 61.7 square miles) and it has an estimated  population of 35,000. Its capital is Vaduz; the biggest town is Schaan.

Liechtenstein is the smallest  German-speaking country in the world, and the only alpine country to lie  entirely within the Alps. It is also the only German-speaking country  not to share a common frontier with Germany. It is a constitutional  monarchy divided into 11 municipalities. Much of Liechtenstein's terrain  is mountainous, making it a winter sports destination. Many cultivated  fields and small farms characterize its landscape both in the north  (Unterland, lower land) and in the south (Oberland, upper land). The  country has a strong financial sector located in the capital, Vaduz, and  has been identified as a tax haven. It is a member of the European Free  Trade Association but not of the European Union. Liechtenstein is the  richest country in the world on a per-capita basis. 
Link06 - Monaco - 33,000
Monaco en-us-Monaco.ogg, officially  the Principality of Monaco (French: Principauté de Monaco; Monégasque:  Principatu de Múnegu; Italian: Principato di Monaco; Occitan: Principat  de Mónegue), is a small sovereign city-state located in South Western  Europe on the northern central coast of the Mediterranean Sea. It is  surrounded on three sides by its neighbour, France, and its center is  about 16 km (9.9 mi) from Italy. Its area is just under 2 km² with an  estimated population of almost 33,000.
Monaco is the name of the  country and its capital (and only) city. It is famous as a tax haven,  and wealthy foreigners make up the majority of the population, around  84%. Monaco is a constitutional monarchy and principality, with Prince  Albert II as head of state. The House of Grimaldi has ruled Monaco since  1297, and the state's sovereignty was officially recognized by the  Franco-Monegasque Treaty of 1861. Despite being independent, Monaco's  defence is the responsibility of France. 
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5 - San Marino - 30,000
The Most Serene Republic of San Marino  Italian: Serenissima Repubblica di San Marino) is a country situated in  the Apennine Mountains. It is a landlocked enclave, completely  surrounded by Italy. Its size is just over 60 km2 with an estimated  population of almost 30,000. Its capital is the City of San Marino. One  of the European microstates along with Liechtenstein, the Vatican,  Monaco, Andorra, and Malta, San Marino has the smallest population of  all the members of the Council of Europe.
San Marino is the oldest  recorded sovereign state and constitutional republic in the world,  having been founded on 3 September 301 by stonecutter Marinus of Rab.  Legend has it that Marinus left Rab, then a Roman colony, in 257 when  the future emperor, Diocletian, issued a decree calling for the  reconstruction of the city walls of Rimini, which had been destroyed by  Liburnian pirates. The constitution of San Marino, enacted in 1600, is  the world's oldest constitution still in effect. 
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4 - Palau - 20,000
Palau en-us-Palau.ogg,  officially the Republic of Palau (Palauan: Beluu er a Belau), is an  island nation in the Pacific Ocean, some 500 miles (800 km) east of the  Philippines and 2,000 miles (3,200 km) south of Tokyo. Having emerged  from United Nations trusteeship (administered by the United States) in  1994, it is one of the world's youngest and smallest sovereign states.  In English, the name is sometimes spelled Belau in accordance with the  native pronunciation. It was formerly also spelled Pelew. 
Link3 - Tuvalu - 12373
Tuvalu , formerly known as the Ellice  Islands, is a Polynesian island nation located in the Pacific Ocean,  midway between Hawaii and Australia. Its nearest neighbours are  Kiribati, Samoa and Fiji. It comprises four reef islands and five true  atolls. Its population of 12,373 makes it the third-least-populated  sovereign state in the world, with only Vatican City and Nauru having  fewer inhabitants. In terms of physical land size, at just 26 square  kilometres (10 sq mi) Tuvalu is the fourth smallest country in the  world, larger only than the Vatican City at 0.44 km2 (0.17 sq mi),  Monaco at 1.95 km2 (0.75 sq mi) and Nauru at 21 km2 (8.1 sq mi).

The first inhabitants of Tuvalu  were Polynesian people. The islands came under the UK's sphere of  influence in the late 19th century. The Ellice Islands were administered  by Britain as part of a protectorate from 1892 to 1916 and as part of  the Gilbert and Ellice Islands Colony from 1916 to 1974. In 1974, the  Ellice Islanders voted for separate British dependency status as Tuvalu,  separating from the Gilbert Islands which became Kiribati upon  independence. Tuvalu became fully independent within the Commonwealth in  1978. 
Link02 - Nauru - 10,000
Nauru (pronounced, officially the  Republic of Nauru and formerly known as Pleasant Island, is an island  nation in Micronesia in the South Pacific. Its nearest neighbor is  Banaba Island in Kiribati, 300 km to the east. Nauru is the world's  smallest island nation, covering just 21 square kilometres (8.1 square  miles).
Settled by Micronesian and  Polynesian people, Nauru was annexed and claimed as a colony by the  German Empire in the late 19th century. After World War I, Nauru became a  League of Nations mandate administered by Australia, New Zealand, and  the United Kingdom. During World War II, Nauru was occupied by Japanese  troops who were bypassed by the Allied advance across the Pacific, and  after the war ended, it entered into trusteeship again. Nauru was  declared independent in 1968.
Throughout the first half of the  20th century, Nauru was a "rentier state". Nauru is a phosphate rock  island, with deposits close to the surface, which allow for simple strip  mining operations. This island was a major exporter of phosphate  starting in 1907, when the Pacific Phosphate Company began mining there,  through the formation of the British Phosphate Commission in 1919, and  continuing after independence. This gave Nauru back full control of its  minerals under the Nauru Phosphate Corporation, until the deposits ran  out during the 1980s. For this reason, Nauru briefly boasted the highest  per-capita income enjoyed by any sovereign state in the world during  the late 1960s and early 1970s. When the phosphate reserves were  exhausted, and the environment had been seriously harmed by mining, the  trust established to manage the island's wealth became greatly reduced  in value. To earn income, the government resorted to unusual measures.  In the 1990s, Nauru briefly became a tax haven and illegal money  laundering center. From 2001 to 2008, it accepted aid from the  Australian government in exchange for housing an illegal migrant  detention center that held and processed asylum seekers trying to enter  Australia.
From December 2005 to  September 2006, Nauru became partially isolated from the outside world  when Air Nauru, the only airline with service to the island, ceased to  operate. The only outside access to Nauru was then by ocean-going ships.  The airline was able to restart operations under the name Our Airline  with monetary aid from Taiwan.
On  15 December 2009 Nauru became the fourth country to recognise Abkhazia,  and on 16 December recognised South Ossetia, regions of Georgia which  had been de facto independent since the early 1990s and were recognised  as such by Russia after the brief Russia-Georgia summer war of 2008.  Reports suggest that this decision netted Nauru Russian aid of around  US$50,000,000. 
Link01 The Vatican City - 800
Vatican City en-us-Vatican City.ogg,  officially the State of the Vatican City (Italian: Stato della Città del  Vaticano, pronounced, is a landlocked sovereign city-state whose  territory consists of a walled enclave within the city of Rome, the  capital city of Italy. It has an area of approximately 44 hectares (110  acres) (0.44 km2), and a population of just over 800.
Vatican City is a city-state that came  into existence in 1929. It is distinct from the Holy See, which dates  back to early Christianity and is the main episcopal see of 1.147  billion Latin and Eastern Catholic adherents around the globe.  Ordinances of Vatican City are published in Italian; official documents  of the Holy See are issued mainly in Latin. The two entities even have  distinct passports: the Holy See, not being a country, only issues  diplomatic and service passports; the state of Vatican City issues  normal passports. In both cases the passports issued are very few.
The Lateran Treaty in 1929,  which brought the city-state into existence, spoke of it as a new  creation (Preamble and Article III), not as a vestige of the much larger  Papal States (756-1870) that had previously encompassed central Italy.  Most of this territory was absorbed into the Kingdom of Italy in 1860,  and the final portion, namely the city of Rome with a small area close  to it, ten years later, in 1870.
Vatican City is an  ecclesiastical or sacerdotal-monarchical state, ruled by the bishop of  Rome—the Pope. The highest state functionaries are all Catholic  clergymen of various nationalities. It is the sovereign territory of the  Holy See (Sancta Sedes) and the location of the Pope's residence,  referred to as the Apostolic Palace.
The Popes have resided in the  area that in 1929 became Vatican City since the return from Avignon in  1377. Previously, they resided in the Lateran Palace on the Caelian Hill  on the opposite side of Rome, which site Constantine gave to Pope  Miltiades in 313. The signing of the agreements that established the new  state took place in the latter building, giving rise to the name of  Lateran Pacts, by which they are known.
 Source: http://pavanmickey.blogspot.com/2010/08/very-least-populated-countries-in-world.html