For what it's worth, if you're using a cable lock, just save the weight and use a small padlock rather than a stout one. Anyone cutting a lock is just going to cut your cable first, no matter the lock, because they're so easy to cut.

I did like gerryl mentioned and sprayed my bike flat black, sanded off derailer logos, and taped over the cranks and wheel logos. You'd have to be walking around trying to pick out nice parts on a bike to notice that my bike is actually nice.

One idea I toyed with was using a Kryptonite lock with decently thick chain links, but taking the sleeve off and replacing most of the length of chain with aluminum chain. Then replace the sleeve and no one will ever know you don't have a heavy duty Kryptonite, but with half the weight. Unfortunately I haven't found bulky, thick AL chain anywhere. I guess there's really no reason for it to exist, so it makes sense...