I agree on the Talonsoft series for hex-gamers. If attrition hadn't killed off my old cd's I'd still be happily playing them all, alas I'm down to Antietam.
There is another independant group making an American Civil War genre game, check out
http://www.madminutegames.com and see what they have been up to. It looks promising but needs alot of work from the videos they have available. They hope to have it out sometime this year.
Another idea was also mentioned if you are into that period is reenacting. I did that for many years while in Georgia and now am about to get back into it with a new unit here in Maryland. Why just play the games when you can get a flavor and feel of the (somewhat) real thing?
Any gamers out there remember the Avalon Hill Gettysburg board-game? Talk about a paperwork nightmare!