Clementine Image Browser: Data server from the Clementine space mission. Contains images, search tool, time-lines, and mail.
IAU: Minor Planet Center: The official body that deals with astrometric observations, and orbits of minor planets, asteroids, and comets.
National Space Science Data Center: Provides access to a wide variety of astrophysics, space physics, solar physics, lunar, and planetary data from NASA space flight missions, in addition to selected other data, models, and software.
PDS - Planetary Data System: Solar system exploration science data archive, maintained at JPL.