I know that Weird Al has been getting a lot of attention on this board lately. But don't forget what They Might Be Giants have contributed to that particular brand of music--you know, the kind that seems to be especially loved and appreciated by nerds and geeks across the universe?
Personaly, I prefer TMBG because their sense of humor is extremely clever and subtle, whereas Weird Al's is much more obvious and contrived. I also love the irony of writing sad songs shrouded by metaphores and upbeat music (read some TMBG lyrics without the music sometime. It's kind of disturbing in a weird, humorous way.)