I have a teenager son and he likes X-box (Halo especially) so I digitized and embroidered blocks for him that showed some of the awards that he had received on the game.
He also likes to make movies so I made him the Strip Show quilt (think that's what it's called) out of bright colors..
He also likes lizards and planes.. also has a duvet cover that covers the BTB quilt he had when he was little.
If you can find out just a few things they like, then you can go from there..
HTH