Webster Gateway Server - online dictionary at Stanford Knowledge Systems Laboratory

Principia Cybernetica Glossary

VHG Home Page - virtual hyperglossary.

OneLook Dictionaries - by Bob Ware.

yourDictionary.com - as was: A Web of On-Line Dictionaries

Virtual Reference Sites - Frank Vadala.

xrefer - the web's reference engine.

Philosophy

Philosophy Dictionaries and Glossaries by Peter Suber

Meta-Encyclopedia of Philosophy at Digital Text International

The Stanford Encyclopaedia of Philosophy edited by Zalta et.al.

The Internet Encyclopaedia of Philosophy edited by Jim Feiser

A Dictionary of Philosophical Terms and Names by Garth Kemerling

Glossary of First-Order Logic by Peter Suber

The Ism Book - a Field Guide to the Nomenclature of Philosophy

Dictionary of Philosophy of Mind - sponsored by the Philosophy- Neuroscience-Psychology program of Washington University in St. Louis.