The best resource is the library.  Books and journals still have a degree of quality control that is often lacking on the internet (anyone can put up a web page).  With that caveat in mind, there are of course some valuable resources at your disposal.
The bulk of these sites are for your research.  But why are you doing research?  Probably to help you write a paper.  There's a knack to writing good philosophy papers.  I highly recommend this manual for philosophy students "How to Write Philosophy Papers," by Dr. William O. Stephens at Creighton University.

Useful Philosophy Links:

Begin with the Philosophy Pages Dictionary of philosophical terms.  The Philosophy Pages main page is also a great reference tool.
Episteme Links is a very useful resource.
The Stanford Encyclopedia of Philosophy is useful.
The American Philosophical Association is a good place to know about.

General searching: use the Yahoo Philosophy page or the Google Philosophy page.

This Plato interactive learning resource is very good.  (This link seems to be down - I'll investigate)
Non-Contradiction.com is a very thorough Aristotle resource.

The Philosopher's Magazine is a good resource also, as well as Philosophy Now.
Open Court's Philosophy and Popular Culture Series

Watch for future updates as I learn of more useful links! Also, check other faculty members’ pages!

Related academic resources:
Perseus Project is an online classics resource.
Yale’s Avalon Law Project has documents on Law and Diplomacy.

Philosophical fun:
The Kant Song (courtesy of Prof. Roderick T. Long, Auburn University)
Woody Allen on Nietzsche's Diet Book
Monty Python's Argument Clinic sketch.
Monty Python's "Bruces" sketch, aka Australian Philosophy Dept sketch.  That's supposed to end with the Philosophers' Drinking Song, but that's now a different clip.
International Philosophers' Soccer match, Germany vs Greece
Using Logic to determine whether someone is a witch.
Medieval political philosophy via Monty Python
David Chalmers Philosophical Humor page
Jazz vocalist Patricia Barber's terrific song about the pleasures of philosophy "I Could Eat Your Words" is not to be missed.  (Go to the linked site, click on "Listen to the Verse Player (lower left of the screen); on the lower left of that window, click on "I Could Eat Your Words" and then the play button (looks like a play button on a tape deck).