I just finished reading "Fool" by Christopher Moore, after having read "Lamb" and "You Suck." If you haven't read any of his books, really, you're missing out. They are literally laugh out loud funny. Thank you, Caitie, for introducing him to me!
On the back flap of "Fool" he provides an email address to contact him. Seeing as I've written a comedy novel myself (albeit YA) I figured I'd write to him and see if he had any advice. Surprisingly, within 24 hours he had written back, and we exchanged a couple of emails back and forth!
He had some great advice about letting inspiration in at all hours of the day and night, writing everything down, where funny bits can come from, and how to decide what to keep and what to cut (perhaps the most valuable bit for me -- as an unpublished author, he very strongly suggested making sure EVERYTHING in the first 25 pages fits the story - even if it's funny as hell, if it doesn't fit the story, cut it).
His emails were funny and self-deprecating, while honest and helpful at the same time. I really appreciated the time he took to help out a novice writer -- so again, helping him out with a bit of a plug -- if you haven't read any of his books, seriously, go pick one up. I plan on reading more of his work as soon as I can!