I once had an idea to "hijack" cars/bikes. The criminal would install a lock on the car/bike, along with a note containing instructions on how to pay. Upon payment, they receive the key to the lock (it's theirs to keep, as a bonus) in the mail. Would be easier with a digital where the criminal would just give the victim the combo.<p>Anyway, my point is there's a lot of ways to scam people.