I have a suggestion.
Not a reputation whore, but I have seen that some users accept an answer but not upvoting it. Two examples that recently happened to me are here and here. The way I see it is that when I accept an answer I upvote it.
As you can see users are new to Stack Overflow (reputation very low) and probably don't know how it works.
My suggestion is find a way of improving this by:
- Putting a message on question acceptance.
- Auto voting up accepted answer if user is pretty new (reputation under 100 or similar)
Against it I am not sure on the % of accepted answers without votes so not sure if this is needed or not...