These "bicycle handcuffs" look like a pretty good solution to a lot of bike-locking problems (though they wouldn't be much help in locking your bike to a telephone pole or wide light-post). I can't evaluate the manufacturer's claims about the material's hardness or the lock's efficacy, but the theory appears sound:
Link (via Red Ferret)
The heavy-duty cuffs attach around the fork and disc rotor so would-be thieves can't make off with your bike unless they’re armed with some kind of Fort Knox-busting wonder weapon. This nifty arrangement means you won’t have to fool around taking off your wheel for full lockdown. You don’t even need to use the keys to secure your bike, just click the cuffs using the integrated buttons.