You know, comic books have always made me want to know whether these things are actually dangerous or not. The answer seems to be 'maybe', depending on which version of theoretical physics you're down with. Not that that stops anyone...
Well, this person seems to think they're dangerous. But only the really, really, really big ones (specifically, CERN's LHC). Oh well; if we all get eaten by a black hole, at least we will have died FOR SCIENCE!