I hate to suggest this because of what the tag fairy stuck on me, but...
Weird Al. Very funny and clean...but unclean enough to be funny to a young boy. E.g., (sung to the Avril Lavigne tune) "why'd you have to go and make me so constipated..." That's about as raunchy as it gets.
Now, if that humor bothers you, not good. We think he's very funny. Even saw him in concert over the summer. My 11 and 8 year olds are so into his music (and videos, and movie...) as are ALL of their friends. It gets on my nerves occasionally, but am happy for music that's fun for them, funny, and not objectional.
They also really like Nickleback and Creed.
For a young CD collector, soundtracks are also very good. If there is a movie he's into that has good music, he'd enjoy the CD because he'll have a point of reference for the music. The Holes soundtrack is fantastic.