NOTE: Some of these links have not been checked for a while, may need updating.
China National Space Administration CNSA (English pages)
http://www.cnsa.gov.cn/n615709/cindex.html
European Space Agency ESA
http://www.esa.int/ESA
Indian Space Research Organisation ISRO
http://www.isro.org/
Japan Aerospace Exploration Agency JAXA (English pages)
http://www.jaxa.jp/index_e.html
NASA
http://www.nasa.gov
NASA Spaceflight
http://www.nasaspaceflight.com
RosCosmos Russian Space Agency English pages
Sadly, do not seem to be maintained anymore.
http://www.roscosmos.ru/
SpaceX
The first commercial company to send a capsule to the ISS and bring it back. The Dragon is potentially capable of seating 7 astronauts.
http://www.spacex.com