I haven't seen anything from Frankie Boyle, but I do have a thing for dark/surreal comedy. Doug Stanhope is morbidly funny and offensive, he's one of those comedians that's in-your-face with his opinion. That's normally not my style but he's brilliant in that he can break your heart but keep you laughing at the same time. Mitch Hedburg isn't really dark, but if you like drugs and enjoy the absolute bizarre, he's your guy. I think he's brilliant. (Well, was.)
It takes a lot of genius to be a good stand-up comedian. Silent moments during a comic's show are just excruciating.