http://www.youtube.com/watch?v=o-LWGJzglho

key locks take a bit longer, and a bit more skill, but not much
http://www.youtube.com/watch?v=Fvjp0...eature=related

http://www.youtube.com/watch?v=w_Gch...feature=fvwrel

I can't find it now, but there was a video about freezing older u locks with compressed air cans and shattering them with a hammer.

Moral of the story, locks only slow down criminals. Keep an eye on your bike.