Related, but about the Bible rather than atheism per se, are Bart Ehrman's books.

Anything by Dawkins of course, but everyone will say "The God Delusion", for something different, fun, and not so long, try "Unweaving the Rainbow". For something very easy, especially if you want to help say a teenager who will like a soft gentle slightly woo route out of theism, try, Usuala Goodenough, "The Sacred Depths Of Nature". And despite the title Andre Comte-Sponville, "The Book Of Atheist Spirituality" does not contain any woo, but does cover all the bases in a short easy read.

The God Argument by A.C. Grayling

Read not exactly...but I do listen to audio books. Currently listening to The Foundational Faslehoods of Creationism by Aron Ra. He also has the video series on YouTube.

The bible. Read with objectivity, it's the best argument against religion.

Dead Prez, hip hop albums

Agnostic books as well