This is a long shot but, could a Guild Killing board be added? Basically your kills that you get on a tag will count only for that tag. If you swifch tags, the kills you got on the first tag stay with it, and any kills you get on the second tag only count toward that tag. Maybe the top 3 PKers in the top 3 guilds could earn a prize or something? Even without prizes it'd sill be cool, plus it gives guilds a much needed real extra activity.

Edit:
Maybe it's a little less of a long shot than I thought then? Pls add this would be cool, I'm sure people would like it.