OneLook.com, the meta-dictionary (I never start up Firefox without it)
The Internet Movie Database (I append "IMDB" to most movie and actor/actress searches)
WikiPedia (... and I append "Wikipedia" to nearly every other search in Mozilla's Google sidebar box)
Cool web projects:
The Tree of Life Web Project
ETA, 10:55 CDT Sat 28 May 2005:
Belated happy birthday, sui_degeneris!
Sowwy I flaked! *thwaps self with fins*