What is a Freethinker? from the Freedom From Religion Foundation
An introduction to the beliefs of freethinkers.

The Essence of Agnosticism by Bill Schultz
A good description of epistemological agnosticism.

What is Atheism Really All About? by Richard Carrier
Quick and simple answers to common questions about atheism.

An Introduction to Atheism from The Atheism Web
A gentle but thorough introduction to the different varieties of atheism and agnosticism.

Gentle Godlessness - A Compassionate Introduction to Atheism by Paul O'Brien
"I am appealing directly to two parties: theists, specifically Christians, and atheists. To Christians, I ask that they please make an effort to reconsider atheism if they have already condemned it. To atheists, I make an especially avid plea to reconsider their own position as well. I am tired of heated debates that lead to personal insult. I find Christians who are close-minded frustrating, but I find atheists who speak sarcastically and disrespectfully equally disappointing."

Is There Anything Good About Atheism? by by Adrian Barnett
Discusses some of the many positive aspects of atheism.

What an Atheist Ought to Stand For by Richard Carrier
"I enumerate the values that should be held by all atheists. If you want to know what my value system is based on, and what sort of moral standard I hold my life to, you should read this essay."

A Fish Did Not Write This Essay by Richard Carrier
Examines the differences between faith in God and "faith" in reason.