One idea that is foolproof (if implemented PERFECTLY)- make it so that people on your ignore list can't be pugged up with you. This requires little explanation as to how it works. Greifer? Ignore. Never have to deal with them again. Eliteist? Same thing. Guy with chat closed and thumbs up his ()? Same. Totally foolproof, and can't be abused.
When in doubt, (hehe) c4!
This sig dedicated to the many random objects the Mythbusters crew has blow to smitherines