The Internet Encyclopedia of Philosophy
A helpful source of background materials on many issues and thinkers, with entries arranged alphabetically.
The Perseus Project
A guide from Tufts University to classical Greek and Roman philosophy, art, literature, etc.
The Socrates Project
An annotated electronic text of Plato’s Apology, Euthyphro, Crito, and the death scene from the Phaedo, intended especially to help beginning readers of these works.
Larry Hinman’s Ethics Updates
Includes many discussions of ethical issues and various aspects of ethical theories, including bibliographic information; also includes links to some primary texts in the history of philosophy.
Other Philosophy Departments in the US
The American Philosophical Association’s listing of departments of philosophy in the United States