I have heard that Bart Ehrman is a good author with several books out that fit your description. I have one queued up to read; Misquoting Jesus, which is, according to its byline, "The Story Behind Who Changed the Bible and Why". Not a heavy read, either, weighing in at just over 200 pages.
You might also try Iron Chariots Wiki. This site is maintained by the ACA (the same folks behind The Atheist Experience podcast) and is "intended to provide information on apologetics and counter-apologetics."
I think Ehrman is an excellent recommendation.
Also check out:
Who Wrote the Bible- Friedman
The Rejection of Pasal's Wager- Tobin (book and website)