I agree, things that aren't fun to buy but everyone has to like gas gift cards or even grocery store gift cards. Nerf guns are always a hit, theyre pretty cheap at wal mart and target. Movie tickets are a great idea!! Also maybe a stocking with things they use like deodorant, their cologne, gum, a new razor, etc.
Like someone else said, if they are gamers and you know what system they have, a new controller or a subscription to the online network is a big hit.