Well, in my not-so-young life I've done a bit of reading on the war, some of the books have been mentioned above. My favorite all-around general histories of the war have been McPherson's Battle Cry of Freedom, Foote's trilogy, both Catton trilogies. I think Baltis has nailed down the best as far as credible, authoritative, peer-reviewed general histories of the war...can't get much better than those authors, my opinion of course.
As far as specific battles/campaigns I liked Wiley Sword's "Confederacy's Last Hurrah" on the Spring Hill, Franklin, Nashville campaign of the AOT, Larry Daniels' book on Shiloh, Gordon Rhea's books on the Wilderness campaign and there are others, can't remember all the titles right now. As they come to me I'll post them up here, they were very good, informative reads. Unfortunately my books are all MIA after a messy divorce, and that's a tragedy but stuff happens in life, am I right? At some point I'd like to replace many of them if I'm able to.
Good thread, I've already seen some titles posted that I'd love to read. Keep 'em comin'.