Randy,
I haven't heard of a book being written recently or in the works regarding the men of the 12th Indiana Infantry. I do have this URL that has been of great help to me and my living history group: http://yesteryear.clunette.com. This website has several personal accounts and a full web rendition of Chaplain Gage's book on the 12th Indiana. With regards to the living history organization I belong to, we have chosen to represent Company E, 12th Regiment Indiana Volunteer Infantry. We've been in existence for about 1 1/2 years and we are always looking for more research info on the regiment we strive to represent. You have a real treasure in your great uncle's affects. I'm gratified that you have them displayed appropriately at the Carter House. I hope that someone will, someday, write a modern narrative of these brave men. Contemporary accounts and recollections tend toward a subjective view. These are invaluable resources, but when taken out of context, they can lead to a distorted view of events as they happened. They are always enjoyable from the personal perspective and I'd love to see them compiled and framed in a readable and historically overseen narrative. Here's hoping...
Until then check back often, I'm hoping to post our own website with the research we've done so far. God bless you, sir. Perry