As I was locking my bike up yesterday, an Edinburgh University security man gave me various bits of friendly advice - most of it was predictable and along the lines of my lock not really being sufficient as it is a cable lock.
My lock is pretty rubbish but it used to defend against opportunistic of my not particularly desirable bike. Previously I had locked it as tightly as possible through both wheels, frame and Sheffield stand. I was in favour of locking as tightly as possible as when it is windy the bike had a tendency to become vertically challenged.
Apparently the easiest opportunistic way to nick a bike (as evidenced by CCTV apparently) with a fairly rubbish lock on a sheffield stand is to use the bike as leverage to forcefully break the lock - providing it is fairly tightly locked up. So I shall in future be trying to defend against this by leaving quite a bit of slack in the lock - then it is much hard to use the bike itself to break the lock.
This may of course be old news to everyone, but I felt it quite useful advice.