Critique of Religion and Philosophy, by Walter Kaufmann. I'm only about 20 pages into this one, though I have leafed through the rest of the book to see what I was getting into. The book seems to be a hodge-podge of reflections by Kaufmann on all things religious. I wasn't really eager to start this one, but it's been sitting on my bookshelf for a couple years, and I figured I might as well give it a shot.
The Six Ways of Atheism: New Logical Disproofs of the Existence of God, by Geoffrey Berg. Got this one from the local public library. This book seems to be about the main evidences that atheists put forth to disprove the existence of God, only (so far as I can tell) Berg constructs the arguments in less philosophical language, so that the book is a bit more accessible than such books usually are.
Western Atheism: A Short History, by James Thrower. Also got this one from the library, and it's the second time I've read it. I needed it again to get some leads on who to look to as far as early agnosticism, particular in ancient Greece. It's a fun, short read, though it gets a tad boring in the middle ages when the author is talking about pantheists and such.
The Varieites of Scientific Experience: A Personal view of the Search for God, by Carl Sagan. Just started this one, and have only read the editor's introduction. Seems like it'll be a good one, though.