Is it perhaps an idea to add an "accept as answer" option to the forum?
One advantage is you can easily tell apart which questions have been answered from the ones that might not have been.
Another feature could be you can assign a score to each member. It should be presented as a means to determine the probable quality of the answer; people that have a high rating are more likely to be active and provide acceptable answers. Even if they only go for the easy answers they'd still be good there...
I liked the list at the Delphi pages in which someone called "Mr Baseball" was the undisputed answer wizard solving the very hard and very easy question. I was much lower on the list, but because I wanted to get higher I spent more time at answering other peoples questions (which you have to do right to get accepted as the correct answer)
But the focus should lie on adding extra information about thread and poster.
