A really cool feature would be a system of badges to drive beneficial member behavior. Don't get me wrong -- points for correct answers are the best thing since sliced bread, and we and our members love them. But they are limited to asking & answering questions.
But I'd love to have a page like this on our site -- probably inspired by some of the gaming sites -- all sorts of badges for behaviors and accomplishments: http://stackoverflow.com/badges They capture all sorts of interesting behavior.
- Completed all profile fields
- First to flag a post
- Rated a document 1/10/100/1000 times
- Given good/correct answer points 1/10/100/1000 times
- Left 1/10/100/1000 replies
- Left a correct answer 1/10/100 times
- Posted a question / thread / document / blog post - 1/10/100 times
- Answered a question more than 60 days old
- 100 / 1000 / 10000 views on one of your pieces of content
- Created a tag used by 50 other items
- Active member for a year
We can all probably think of more...