(I think the point was choosing BEFORE you knew the catch, right? Although the powers suggested by many of this thread because of the catch were pretty funny - I mean, those besides invisibility...)
I wasn't expecting the catch, so I chose Telekinesis. Mind over matter ftw! Anyway, even naked, I could make a shield of stuff around me, so no one would notice it. I could use it specially at home! Making my meals while on the computer, or in bed would be awesome! Cleaning the house would be pretty easier too.