Spy magazine used to run a feature called "Logrolling In Our Time", which I always found hilarious. No, it wasn't about the lumberjack contest of surefootedness--Wikipedia defines it as "suspicious or humorous examples of mutually admiring book jacket blurbs by pairs of authors". I haven't found so many blurbs with suspicious mutal praise by authors of each other's work, but I have found some entertaining blurbs, which I will occasionally pass on to you.
Here's one from the back of Patricia Marx's book Him Her Him Again The End of Him:
"If you're like me, you read a blurb and think, Oh, I didn't know they were friends. But I hardly know Patty--we had dinner once (with other people, and all she had was a Diet Coke). So you can believe me when I say: This may be the funniest book I've ever read. The funniest. Ever. And keep in mind I didn't write this blurb as a favor to Patty. I did it for you. So you'd be able to pick out the funniest book in the store and take it home and laugh your head off." --Melissa Bank, author of The Girls' Guide to Hunting and Fishing
And it's true--Patricia Marx's book is pretty damn funny.