IAU - Minor Planet CenterSave
Is responsible for the efficient collection, checking, and dissemination of astrometric observations and orbits for minor planets and comets, via the Minor Planet Circulars (issued monthly) and the Minor Planet Electronic Circulars (issued as necessary). http://cfa-www.harvard.edu/iau/mpc.html
Minor PlanetSave
Dedicated to astronomical imaging and positional data, and includes information on observatories, news, images, star charts, fits data, and shareware. http://www.minorplanet.org/
Small-Body Orbital ElementsSave
Provides access to orbital elements for numbered asteroids, unnumbered asteroids, and comets with element tables using a custom generator (using the current DASTCOM database) or ASCII files. http://ssd.jpl.nasa.gov/?sb_elem