Get some skunk oil from some sort of hunting shop and a syringe... Inject it here and there in the seats of his car
Get video of him either having sex or even better smoking pot or doing drugs. Send copies to his entire family on Xmas.
Take some grass killer and squirt huge letters of whatever message you would like to make across his lawn.
Uhm... I'm tired. I can't think of many right now but that should give you a good start