How about a badge that encourages users to give back as many votes as they get?
I did a quick (not 100% accurate) go on data.se.
The basic rules are:
- Minimum amount of rep to be considered (5k or more)
- Voted on at least (rep / 10) posts.
So, if you have 5000 rep, you are expected to vote up 500 posts to get this badge. And it slides.
A few twists:
- Make it revocable
- Exclude wiki
- Gold version for high rep users (10k and up)
- Perhaps look at an amendment that allow some very high rep users to get it, http://stackoverflow.com/users?tab=voters&filter=all, Marc is perhaps one of the more balanced users, it would be more that fair for him to get it.
I think this kind of badge encourages the right people to vote, and helps give something back to the people who vote a lot.
Voting drives the economy of Stack Overflow and this would potentially help make it more sustainable.