You ever seen Ninth Gate? it's based on a book called The Club Dumas. Unlike the movie, the book is totally funny.
Christopher Moore writes pretty funny, quick reads, including Lamb: The Gospel According to Biff. I was googling around to find and excerpt of his beatitudes, which are pretty funny, but I couldn't find it and am too lazy to go grab the book and type them up myself. They include trying to decide whether someone gets the kingdom of heaven, a fruit basket, or an "attaboy" from god.
Charles de Lint writes modern, urban fantasy. Most of it is heart-warming and some even a bit tear-jerking, but within his collections of short stories are some decent humor. Particularly the crow girl stories. But they're all very feel-good, quick reads, if you're down.