This probably isn't for everyone, but for those that park on the street overnight this would be pretty cool. What do you think?

 

It would be a pain in the ass to carry your steering wheel around everywhere, but for those times when you would be gone for longer periods of time it might be worth it, since most thieves won't be carrying a spare steering wheel around.
Of course they could always tow it.

 

Just make a custom strap and walk around with it hanging off your shoulder!