Hey!
I for one am a pretty big fan of the entire kills idea. I have almost 5000 now, and loved that the first few hundred I would have a congratulations for it, but I was also going to suggest maybe some sort of symbolic bonus would be cool, to entice people to make more kills?
like giving 100gold or something for every 1000kills!
maybe that's even too much, but just bouncing ideas off the wall!