Thanks for all the suggestions guys. I will check them out.
Well, I guess different folks have their own ideas as to what they consider "dialogue-heavy". If you were reading a piece from a book and thought to yourself, boy, there's a crap-load of dialogue there in one hit, and you found that you were saying it yourself regularly throughout the course of the book, then I guess you could consider it a "dialogue-heavy" book. (To put it simply.)
Then again, maybe you've read a book of that kind, but have not noticed the long stretches of sheer dialogue because the author has done such damn fine job. They are the books I'd love to hear about.
Cheers!