Syndey Penner’s site has a wealth of philosophical resources, not the least of which is a page with links to great philosophy resources around the web. Rather than try to reinvent the wheel, I’ll just paste the following (slightly modified) text from his site:
“The philosophy site that I use most frequently is the Stanford Encyclopedia of Philosophy. Entries are generally quite in-depth and serve as useful introductions to recent work in the topic in question (they also have useful bibliographies). It is a work-in-progress, though, so there are still quite a lot of gaps in the entries. Entries vary in accessibility. Some are readily intelligible to any reasonably intelligent reader; others assume familiarity with quite a bit of philosophical jargon and technique.
The Routledge Encyclopedia of Philosophy contains far more entries. They’re shorter and usually relatively free from forbidding technical stuff. Access to this encyclopedia requires a subscription, however, so it’s really only of use to members of institutions that have subscriptions.
Jim Pryor has put some excellent resources online: Guidelines on Reading Philosophy, Guidelines on Writing a Philosophy Paper, and Philosophical Terms and Methods (the last item includes some nice examples of good and bad argument forms). These documents provide the best advice that I’ve seen for students who are starting to take philosophy courses and who are puzzled by some of the habits of analytic philosophers.”