He likes music too, so CDs are always a popular gift. IPods are great gifts and if he already has one, there's tons of accessories available. Movies are also always popular with my teenagers.I like to buy books for my kids as well. I typically buy my son some kind of baseball books, just because he's not a motivated reader by nature, so try to encourage it by the subject matter!
If you're looking for a more sentimental gift, a scrapbook is always a fun thing for them, but also lots of work to prepare. I also found my son a beautiful wooden box at a gift shop a couple of years ago. I don't know if it flipped his lid, but it's really nice - handmade - and something he can keep forever. He keeps his watch and a couple pieces of jewelry he has in it.