An accessible introduction to philosophy is the website of TPM: The Philosopher's Magazine. As well as articles, this site contains a library of famous quotes, and a number of philosophical games you can play, such as one which shows how hard a consistent conception of God is, and one about reality and appearance, based on the Matrix. Such games are often called 'intuition pumps'. Here's another one, which quizzes your intuitions on intentionality.
The American Philosophical Society recorded a number of short audio clips about philosophy and philosophical questions. These can be found at No Dogs Or Philosophers Allowed which also contains other philosophically provocative video.
Another 'philosophy for everyone' publication is Think: A Journal of the Royal Institute of Philosophy.
EpistemeLinks is a major resource for all things philosophical. It has thousands of links to texts, blogs, quotes, humor, and even a store of philosophy merchandise.
There are two on-line encyclopedias of philosophy. The smaller and more basic is the Internet Encyclopedia of Philosophy. The larger and more sophisticated is the Stanford Encyclopedia of Philosophy.
If you have a favorite on-line introduction to philosophy, please send it in.