I just discovered a rather interesting tool. This appears to be a site devoted to allowing wireless carriers the ability to colocate equipment at existing cell tower sites. But it's also a handy tool for locating the towers and mapping out coverage.

http://www.sprintsites.com/?

Not only will the database give you lat and long for each tower, but there are actually pictures of both the tower and the enclosures. That's pretty kick ass if you ask me.