There are several types of ISS crews, and the organization changed with the years.
Until 2003
The permanent crews were the main ones : they stayed in the station to maintain it and to carry out scientist experiments. They generally stayed six months in orbit and were composed of three members : two Americans and a Russian or an American and two Russians (alternatively). They were carried by shuttles (Columbia, Discovery, Atlantis or Endeavour).
There were also the « taxi-crews ». A Soyuz is permanently attached to the station to permit the permanent crew to come back on Earth in case of problem. For safety, this ship was replaced roughly every six months. The taxi-crews were made to join the station with a new ship and leave it after a few days with the old one. They were composed of three persons (maximal capacity of Soyuz).
Finally, there are crews for deliveries : supply, new segments, material, ... This crews have a variable composition and can travel with Soyuz or a shuttle.
From 2003 to 2006
On February 1st, 2003 took place Columbia's accident. NASA cancelled all shuttle's flights. Then only Soyuz was available for orbital flights and the organization changed.
Taxi-crews have been suppressed : the changes of safe Soyuz were made with the changes of permanent crews. So the new permanent crew arrived in the station with a new Soyuz, that would serve him for safety, and the previous crew left the station with the old ship.
Moreover, the size of crews has to be reduced to two members, an American and a Russian. These changes concern the crew 7 to 12.
From 2006 to 2009
Because the return of Discovery on August 9, 2005 was succesful, shuttles are used again. It permitted to have permanent crews of three persons again (since 13th crew). However, the composition didn't become exclusively American and Russian, by giving access to European astronauts (a German one arrived on July 6, 2006).
Moreover, the idea of changing the Soyuz in the same time that the crew remained. Since this change, crews are changed in two steps. Two members are replaced by two persons coming with Soyuz ; the third crew member is replaced later, generally with a shuttle.
Since 2009
The return of shuttles also permitted to build the station again (Soyuz can't carry big segments), so in 2009 its capacity raised to 6 people. Then on May 29, three astronauts joined the 19th crew and they formed together the 20th crew. This event was also the occasion to have for the first time in the station an astronaut of each five partners of ISS (Canada, ESA, Japan, Russia, USA).

So here is the list of permanent crews, adapted from the site Astrocosmos and from NASA. The dates are indicated according to international schedule GMT. For each crew, the first indicated member is the commander. Click on a photograph to enlarge it

CrewArrival to the stationDeparture from the stationMembers
Crew n°1
1st crew
November 2, 2000March 19, 2001William M. Shepherd (USA)
Iouri Pavlovich Gidzenko (Russia)
Sergueï K. Krikalev (Russia)
Crew n°2
2nd crew
March 10, 2001August 20, 2001Iouri Usachev (Russia)
James Voss (USA)
Susan Helms (USA)
Crew n°3
3rd crew
August 12, 2001December 15, 2001Frank Culbertson (USA)
Vladimir Dezhurov (Russia)
Mikhaïl Tyurin (Russia)
Crew n°4
4th crew
December 7, 2001June 15, 2002Iouri I. Onufrienko (Russia)
Daniel W. Bursch (USA)
Carl E. Walz (USA)
Crew n°5
5th crew
June 7, 2002December 2, 2002Valery Korzun (Russia)
Peggy Whitson (USA)
Sergueï Treschev (Russia)
Crew n°6
6th crew
November 25, 2002May 3, 2003Kenneth Bowersox (USA)
Donald Pettit (USA)
Nikolaï Budarin (Russia)
Crew n°7
7th crew
April 28, 2003October 27, 2003Iouri Malenchenko (Russia)
Edward Lu (USA)
Crew n°8
8th crew
October 20, 2003April 29, 2004Michael Foale (USA)
Alexander Kaleri (Russia)
Crew n°9
9th crew
April 21, 2004October 23, 2004Gennady Padalka (Russia)
Edward M. Fincke (USA)
Crew n°10
10th crew
October 16, 2004April 24, 2005Leroy Chiao (USA)
Salizhan Sharipov (Russia)
Crew n°11
11th crew
April 17, 2005October 10, 2005Sergueï Krikalev (Russia)
John Phillips (USA)
Crew n°12
12th crew
October 3, 2005April 8, 2006William McArthur (USA)
Valery Tokarev (Russia)
Crew n°13
13th crew
April 1st, 2006September 28, 2006Panel Vinogradov (Russia)
Jeffrey Williams (USA)
Thomas Reiter (Germany - ESA) : arrived on July 6, 2006, also member of following crew
Crew n°14
14th crew with Thomas Reiter14th crew with Sunita Williams
September 20, 2006April 19, 2007Michael Lopez-Alegria (USA)
Mikhail Tyurin (Russia)
Thomas Reiter (Germany - ESA) : left on December 19, 2006, also member of previous crew
Sunita Williams (USA) : arrived on December 11, 2006, also member of following crew
Crew n°15
15th crew with Sunita Williams15th crew with Clayton Anderson
April 9, 2007October 19, 2007Fyodor Yurchikhin (Russia)
Oleg Kotov (Russia)
Sunita Williams (USA) : left on June 20, 2007, also member of previous crew
Clayton Anderson (USA) : arrived on June 10, 2007, also member of following crew
Crew n°16
16th crew
October 12, 2007April 19, 2008Peggy Witson (USA)
Yuri Malenchenko (Russia)
Clayton Anderson (USA) : left on November 5, 2007, also member of previous crew
Daniel M. Tani (USA) : arrived on October 25, 2007, left on February 18, 2008
Léopold Eyharts (France - ESA) : arrived on February 9, 2008, left on March 24, 2008
Garrett E. Reisman (USA) : arrived on March 12, 2008, also member of following crew
Crew n°17
17th crew
April 10, 2008October 23, 2008Sergei Volkov (Russia)
Oleg Komonenko (Russia)
Garrett E. Reisman (USA) : left on June 11, 2008, also member of previous crew
Gregory E. Chamitoff (USA) : arrived on June 2, 2008, also member of following crew
Crew n°18
18th crew
October 14, 2008April 7, 2009E. Michael Fincke (USA)
Yuri V. Lonchakov (Russia)
Gregory E. Chamitoff (USA) : left on November 28, 2008, also member of previous crew
Sandra H. Magnus (USA) : arrived on November 16, 2008, left on March 25, 2009
Koichi Wakata (Japan) : arrived on March 17, 2009, also member of following crew
Crew n°19
19th crew
March 28, 2009planned for OctoberGennady I. Padalka (Russia), also member of following crew
Michael R. Barratt (USA), also member of following crew
Koichi Wakata (Japan) : also member of previous and following crews
Crew n°20
20th crew
May 29, 2009?Gennady I. Padalka (Russia) : also member of previous crew
Michael R. Barratt (USA) : also membre of previous crew
Koichi Wakata (Japan) : left on July 28, 2009, also membre of previous crew
Tim Kopra (USA) : arrived on July 17, 2009, departure planned with STS-128
Roman Romanenko (Russia)
Frank de Winne (Belgium - ESA)
Robert Thirsk (Canada)