Think: Philosophy
Philosophy resource for beginners. Contains philosophers, schools of thought, and topics.
http://library.thinkquest.org/C0110297/

Larry Hauser's Mostly Modern Philosophical Glossary
Glossary of philosophical terms focusing on modern philosophy.
http://members.aol.com/lshauser2/lexicon.html

Meta-Encyclopedia of Philosophy
A list of philosophical terms and names linked to the major encyclopedias and dictionaries of philosophy on the internet.
http://www.ditext.com/encyc/frame.html

Philosophy Dictionaries and Encyclopedias
Collection of links to philosophy reference sources.
http://lgxserver.uniba.it/lei/dionari/dizengl.htm

Routledge Encyclopedia of Philosophy
Online edition. Free access to sample contents, full access by subscription.
http://www.rep.routledge.com

ISCID Encyclopedia of Science and Philosophy
A free, community developed resource containing information on both science and philosophy.
http://www.iscid.org/encyclopedia/

The Ism Book
A dictionary of philosophies from Peter Saint-André, editor of the Monadnock Review.
http://www.ismbook.com/ismlist.html

Wikipedia: Philosophy
The entrance page to all articles in the philosophy section of the free encyclopedia.
http://en.wikipedia.org/wiki/Philosophy

Dictionary of Sorts
Philosophical terms mostly from ethics and epistemology, edited by Robert Berman.
http://xavier.xula.edu/~rberman/dict.htm

The Philosophical Lexicon
A light-hearted collection of newly coined philosophical terms and phrases with humorous definitions edited by Daniel Dennet.
http://www.blackwellpublishing.com/lexicon/