What is being done in SE land with regards to directing people to question they are likely to be able to make good answers to? I'm going to take a wild guess and say that after getting more people on a site, that is the single biggest lever available for improving the quality of answers people get.
So, my proposal:
Run a "Stack Exchange 'Prize'" contest. (ah la the NetFlix Prize)
The challenge: write a program that can look at the current corpus and then, given a new question including it's tags and comment and maybe an early bird answer or two, predict how well different people will do at answering the question.
Scoring: Each month,just before the data dump goes out, all entries get run vs all (or as many as they can process in a time limit) new questions added after the last data dump (or maybe add a one month delay and run the entries on the month after it is submitted). The program should, attempt to predict who will do how well at answering the question, the closer the program comes to predicting the actual vote distribution of the answers, the better it's score.
The Prize: Bragging rights mostly. The best programs each month get on a high score board. OTOH real goodies every once in a while might be cool to.
Once good predictors start being submitted, they can be used for sorting/filtering the general questions page for each user.