A lot of forums are simply for posting and good posts are rewarded via karma. I would like a website where users can ask for advice and then they get karma if they followup on their decision. I think this would be handy in the QS world.
Here are some example:
1. On health forums, its common for people to say X cured from Y, only to have Y come back a week later.
2. Lots of people buy suppliments, take them for a few days and feel great and then write a stellar review when weeks go by and the suppliment no longer "works."
3. Lots of folks as for advice in relationships only to never hear from that user again. Readers wonder if they took someone's advice and it worked or maybe the person simply died (i kid).
A usecase that comes to mind for myself is probiotics. I think it would be useful to have a forum where you make a post asking what probiotic I should take to help settle my gut. When I make the post though, people can vote when I should return with an update. If I give an update within a day or two of the most upvoted time period, i get extra karma points. Just an example, but I the hope is this would motiviate people to followup on these kinds of posts.