So far the problems don't sound too bad... just really inconvenient. Thankfully you weren't hurt in a collision.

A friend of mine once had his entire 996TT keyed. (they went around the entire car) He had taken special care to park it in the back where no one else had parked. Oddly enough it probably gave the vandals an advantage because of the lack of foot traffic. I agree though, overall the best thing you can do is park well and park next to newer cars without dents, etc.
I remember changing my parking habit after some moron hit my Jaguar with an absolute POS (funny, hitting a POS with a POS). I distinctly remember looking at his car wondering if I should've parked elsewhere... lazy me.