Glossary of Philosophical Terms (Paul Gregory, W & L University)
Leyburn Library's Philosophy Page
Guide to Philosophy on the Internet (Doug Portmore, Cal. State Northridge)
Guide to Philosophy on the Internet (Peter Suber, Earlham College)
Stanford Encyclopedia of Philosophy (Edward Zalta et al., Stanford University)
The Philosophical Gourmet Report (Brian Leiter, University of Texas at Austin)