NASA
Hsf Outreach: How to Become an Astronaut 101
NASA Human Space Flight Outreach page where Lt. Col. Cady Coleman talks about what it's like to be an astronaut and how a passion for high school chemistry led her to become a scientists and shuttle crew member. Her role on the STS-93...
NASA
Nasa: Selection and Training of Astronauts [Pdf]
NASA information on the qualifications required of astronaut candidates and how often astronaut selection is made. Various job descriptions are included and details of several types of training programs are provided.
PBS
Pbs: Space Station Astronaut Training
Part of a PBS series about the International Space Station dealing with astronaut training specifically for constructing and operating the station. Links to other sites with lots of information on the International Space Station (ISS).