(AR)ISS - (Amateur Radio on the) International Space Station
There are many places to look for information about ISS & ARISS (and related programmes and projects, including SAREX and SuitSat), but probably 2 of the best places to start are the ARISS home page (or here for us English speakers) and the ISS Fan Club web site.
From the ARISS home page:
"Amateur Radio on the International Space Station (ARISS) is a volunteer program which inspires students, worldwide, to pursue careers in science, technology, engineering and math through amateur radio communications opportunities with the International Space Station (ISS) on-orbit crew. Students learn about life on board the ISS and explore Earth from space through science and math activities. ARISS provides opportunities for the school community (students, teachers, families and local residents) to become more aware of the substantial benefits of human spaceflight and the exploration and discovery that occur on spaceflight journeys along with learning about technology and amateur radio.
ARISS is an international working group, consisting of delegations from 9 countries including several countries in Europe as well as Japan, Russia, Canada, and the USA. The organization is run by volunteers from the national amateur radio organizations and the international AMSAT (Radio Amateur Satellite Corporation) organizations from each country. Since ARISS is international in scope, the team coordinates locally with their respective space agency (e.g. ESA, NASA, JAXA, CSA, and the Russian Space Agency) and as an international team through ARISS working group meetings, teleconferences and through electronic mail."
Other related programmes include SAREX (Shuttle Amateur Radio EXperiment) and SuitSat (satellite/telemetry equipment in a space suit).