Joel on Software has posted a great reading list of books on business and software management. Check it out.
I've read (and highly recommend):
The Mythical Man-Month
21 Dog Years
Crossing The Chasm
The Tipping Point
I guess I have a ways to go to catch up with Joel. A bunch on is list have been recommended to me by many people already and are either sitting on my nightstand or on my Amazon wishlist.
I'd also recommend checking out:
The Five Dysfunctions of a Team
Good to Great