Sögreni Wire Lock
The wire lock is made of stainless steel plastic-covered wire (6 mm), with ends made into loops using an aluminium or copper fitting. You need a powerful plier to cut this wire. Remember, that most theft of bicycles happens when people "borrow" a bicycle heading home from the pub. This is the answer.
Put the wire around something like a fence or a lamppost. Take one end of the wire and put it through the other. Lock this end on to your normal lock. Now your bicycle is safe, and the lenght of the wire makes daily handling easy.