Aside from maintenance and repair books, I've read some good bicycling-related fiction and memoir/diary type stuff. Tim Krabbe's "The Rider" was great. And I'm going to start Joe Kurmaskie's "Metal Cowboy: Tales from the Road Less Pedaled" as soon as I finish Stephen King's last Dark Tower book.
I'd also like to pick up Mike Magnuson's "Heft on Wheels," since he was one of my university program's professors while I was a student.