Make his life a living hell.
Here are a few suggestions I found that I like:
1) Call a local landscaping company, and have them bring a few tons of granite rocks to their house, and re-landscape their front yard while the person is at work. Have them rip up the current grass or whatnot, and dump rocks there.
2)Go to your local book store or 7-11 and get about 100 magazine subscription cards. Fill each one out with the person's info, and send them off.
3)Phone contractors, swimming pool companies, exterminators, etc. can stop by and give him estimates.
4) Look in swingers magazines for homosexual prostitutes. They are usually advertised as "masseurs" or "friends". Make a list of any that offer house calls and send half of them to the target's house. Also send some to each of his neighbors to create suspicion on their part of who they live next to.
5) Sign the victim up for all the armed forces. The amount of phone calls and literature sent to him is harassment enough.
6) The local post office provides a form for holding mail while you are on vacation. Fill one out since he will be out of town for a month. After that, forward it (with another form) to somewhere in Zimbabwe. If that isn't enough, steal their mail.. incoming and outgoing.
Make him pay for his disrespect!