Nothing real quick but after say 2 months, I think the asker should "owe" 1 rep point for every upvoted answer in a given question.
Using me as an example here:
I asked this question 9+ months ago and haven't accepted an answer yet. If you give a 2 month grace period, I would "owe" 14 SO points for not accepting an answer for 7 months with 2 upvoted answers.
Should I be docked some rep for letting this question go for as long as I have?
To tweak this a little...
Would there be a situation where you would start decrementing rep for this?
- Users with N questions with <M% acceptance.
- Answers upvoted N times with no downvotes (this would show participation from the asker).
EDIT: I removed some of the harsh language. The answers using punish are valid.