While not really worth the $18 it normally sells for, at $9, The Islands of Purple Haunted Putrescence is probably worth it. It's one of those things I've been meaning to review, but stuff that is "meh" is really the hardest to review. If you like something it's easy to review, if you hate something it's extremely easy to review, but if it's meh, it's really work to review something.
Basically, it's a hex crawl (of sorts) over strange, wacky islands with a lot of crazy gonzo stuff. Some of it good, some of it silly, but the good outweighs the bad. Not for the easily offended/traumatized, though.