Have no fear, Dabitch is here!
Seems there's an interesting trend in making people super heroes these days. You're a hero for turning off the water, or turning off the power. You're a local hero if you volunteer to help others like in this incredibly cheap (50 quid!) Scottish campaign. You are a hero if you water your lawn at the right times, say the WWF via Ogilvy in South africa (they also did the stickers campaign linked earlier).
And now, via BBDO for United Way of Chicago, you are a hero for volunteering your time again.
The super hero thing is kinda getting too much play these days innit? If you get one of those ideas, consider another route. You're never going to be able to do it cheaper than that Scottish campaign anyway, so don't even try. ;)