Tween Birthday Theme Ideas

I am currently helping my fiend who has a tween son plan a bday party but the only thing is we can not come up with a theme, what do they like at that age? Is pokemon even cool anymore? Bakugan?How about something superhero-ish like a spider Man theme? I think that was done years ago, oh man this is tough, I hope it wont be this hard when my boys get older, yikes!