Spaceguard Foundation links
Organizations and resources on Near Earth Asteroids.
CBAT/MPC/ICQ Index
That's the Central Bureau for Astronomical Telegrams, the Minor Planet Center, and the International Comet Quarterly. A comprehensive list of lists relating to asteroids, comets, and other celestial objects.
NEAT Home Page
Check and see why it's NEAT.
The Planetary Society Home Page
A public membership organization devoted to a number of space issues, including the Search for Extraterrestrial Intelligence, Planetary exploration, and the discovery of Near Earth Asteroids.