Atheism
The Secular Web - The Secular Web is the ultimate online resource for all aspects relating to Atheism, Agnosticism, Naturalism, Scepticism and Secularism.
BBC Atheism - The BBC provides an overview of the history and philosophy of Atheism.
Wikipedia - The Wiki article covering Atheism
The Atheist Resource - The Atheist's Resouces provides an excellent collection of resources and links for Atheists, Freethinkers and Skeptics.
Internet Infidels - Extensive collection of articles and resources on Atheism.
Positive Atheism (quotes) - A large collection of quotes by Atheists.
Stanford Universtity - Stanford University looks at the differences between Agnosticism and Atheism.
The Infidel Guy - An Atheistic online internet radio station that has some great guest speakers and discussions.
The Freedom From Religion Foundation - The FFRF provides information and legal assistance to Atheistic causes in the US. It's also the home of Dan Barker.
ExChristian.net - This resourceful site contains news, forums and articles related to Atheism and Agnosticism.