Tim Harincar - notebook of a comet hunter
Logs and notes of an amateur astronomer's search for undiscovered comets.
http://www.skyrover.net/notebook/

Comet Observation Home Page
from JPL/NASA
http://encke.jpl.nasa.gov/

Small-Body Orbital Elements
from JPL/NASA. Provides access to orbital elements for the numbered asteroids, unnumbered asteroids, and comets contained in JPL's DASTCOM database.
http://ssd.jpl.nasa.gov/sb_elem.html

Sky and Telescope's Comet Page
Observing comets.
http://SkyandTelescope.com/observing/objects/comets/