I have an idea for ganking. Create a bounty system for gankers. Every time you gank, you get a bounty of "honor" on your head. The amount of "honor" depends on the level difference of gank, and how many times you ganked.
There can be a board in the cities that shows the names of the top 50 gankers and the amount of bounty. So people can go to /who, track down gankers, and kill them which resets their bounty/honor back to zero.
This "bounty" or "honor" is a made-up custom currency. It has no purpose, you cant buy anything with it, and theres no hiscore or ladder for it. It purely exists to track gankers so people can hunt them.
What does this achieve? It turns ganking from an annoying thing sociopaths do, into a fun in-game activity. You can gank to gain notoriety, but you will have people hunting you down, as well as other gankers who want to remain at the top. So gankers start getting ganked the more they gank others. It's a way to balance ganking, while making the whole thing more fun.