NASA
Nasa Space Science Data Archive: Asteroid Fact Sheet
This asteroid fact sheet, supplied by the National Space Science Data Center, provides a table of information on selected asteroids, complete with commentary when appropriate.
Johns Hopkins University
Near Earth Asteroid Rendezvous (Near) Discovery Mission
This is the homepage of the spacecraft NEAR Shoemaker, the first to conduct a long-term, close-up study of an asteroid. The site contains information on the asteroid 453 Eros, including mass, structure, geology, composition, and gravity.