Here are some useful philosophy links:
The philosophy site that I use most frequently is the Stanford Encyclopedia of Philosophy; in fact, I have a keyword set for it in Firefox so that I can do searches in the encyclopedia directly from the address bar. 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.
There are lots of sites that usefully index online texts in particular subject areas. Here are some that I find especially useful: Corpus Thomisticum (very well-done site providing Aquinas's texts in Latin), an extensive bibliography of English translations of Aquinas (at the end of the page, there is also a very useful list of Latin resources), Augustine online in Latin and searchable, links to online Kant texts, the Epistemology Research Guide, and Philosophy of Religion Resources (links to lots of stuff).
EpistemeLinks provides thousands of links to online philosophy resources.
This may not exactly be a philosophy link, but if you want to do something really useful, switch to Linux (clicking on the link will take you to Richard Heck's page describing why he switched and why you should too). While you're at it, consider switching to LaTeX. Charley Tanksley has a splendid how-to-use-LaTeX site specifically for philosophers. But if you insist on staying with MS Word, at least don't make the mistake of thinking that the rest of us would be happy to receive MS Word documents. Contrary to popular opinion, not everyone has MS Word infecting their computers.
And some less useful links:
If you think you're smart and reasonable, try taking this little logic game. Interestingly enough, people with training in formal logic do about as badly as everyone else. If you need cheering up after the results, here are some philosophy jokes. If you have some familiarity with contemporary philosophy, The Philosophical Lexicon is really funny.