General Philosophical Links
An excellent place to start would be the very large Philosophy in Cyberspace site, located at Monash University in Australia
For further searching, an Index of philosophy sites
more general philosphical resources
The Meta-Encyclopedia of Philosophy has indexed the entries from several on-line philosophical encyclopedias and helpful sites. "Compare topics in the most important Encyclopedias and Dictionaries of Philosophy on the Internet."
Boston University philosophy links
Garth Kemerling's A Dictionary of Philosophical Terms and Names
The Internet Encyclopedia of Philosophy
The Radical Academy, Adventures in Philosophy
Stanford Encyclopedia of Philosophy
The Philosophy Pages of Dieter Koehler. The sub-pages are in German, but many links are English. Der Inhalt ist nicht so reich wie die ersten Sites auf Englisch oben.
Online philosophy courses: the History of Philosophy (Ohio State)
a collection of articles on philosophy
Hippias, a search engine limited to philosophy databases on the internet
The Spoon Collective is specializes in mailing lists "dedicated to promoting discussion of philosophical and political issues."