Here are some links and resources that I find useful:
Reference books and material:
Leer Emerson (aka Different) has written the most comprehensive history and reference series on the M14 rifle and its commercial variants. You can buy his books on Lulu - Lulu often has sales and specials, so if you're not in a hurry, watch for a deal.
Amazon has several books available on the M14, here
The Walt Kuleck and Clint McKee book, "The M14 Assembly Guide" is particularly helpful. It's written in a way that even the non-gunsmith can understand.
Tim Strait at Warbirds Custom Guns does excellent work. The rifle at the top of this page was his handiwork. He is very thorough, doesn't recommend unneccesary work and has very reasonable turnaround time. Thell him Randy sent you.
More to come...
If you have information or reference material you think would interest other members of the M14 community, feel free to forward it to me at firstname.lastname@example.org .