This afternoon I read a little 150 page book called Atheism: A Brief Insight by Julian Baggini. I have to say it's a very good introduction to Atheism. Baggini does little to address the classic arguments for God (only covering a few like the argument from design and the cosmological argument) but he explains this by saying that it really isn't intellectual arguments that cause people to believe in God, and I agree with him. He does an excellent job on showing that meaning and morality can exist under the atheistic worldview, and clears up many misconceptions held by both atheists and believers along the way (for instance, explaining that atheism is not simply a lack of belief in god, it is saying that belief in god is not the best explanation for the evidence because, for example, it is not the simplest explanation for the data, atheism is). I think most atheists would agree with that point if they would just reflect on it.
I also managed to find one of the best chapters of Baggini's book posted online.