Open anything, eh?
Finally, a sure-fire way to get rid of those pesky bra hooks!
Seriously though, um... it would be nice to have one key for everything. If I didn't have to waste so much time fumbling with keys and keycards, life would be so much easier. (Plus, if it's the only key I have, I'll never misplace it! It'd be easy to just keep it on my person, unlike my bulky keyring now)
Other than using it to replace all my currently used keys, I'd open a locksmithing business and make a fortune. Have an unbreakable lock that you need open? I'm the only one that can do it. You just can't watch as I'm... er, "picking" the lock.