Hippias: Limited Area Search of Philosophy on the Internet: The most complete place to begin searching for information in philosophy.
Guide to Philosophy on the Internet: Maintained by Peter Suber, Philosophy Department, Earlham College, this is the best one stop shopping source for links to everything. Clearly arranges links by Guides, Philosophers, Topics, Associations, Journals, Teaching/Learning, Etexts, Bibliographies, Mailing Lists, Newsgroups, Projects, Preprints, Jobs , Dictionaries, Quotations, etc. Be warned-it is one huge page. ( There is also a multiple-file edition that loads more quickly, but requires a good bit of surfing to get around.)
Philosophy in Cyberspace: A very nicely, neatly laid-out site with links.
Pascal: The Stanford Encyclopedia of Philosophy article on Pascal's Wager.
Spinoza: The site for Studia Spinoziana which includes links to everything Spinoza.
Locke: Includes information on his life and works and other internets resources.
Leibniz: His biography which includes links to other philosophers.
Leibniz: Includes a listing of works, chronology, and further reading.
Berkeley: For Berkeley studies with links and other information.
Hume: The Hume Society is an international organization whose purpose is to stimulate scholarship on all aspects of Hume's thought and writings.
Kant: Clearly laid out-agreat place to begin further study.