There have been a few efforts to do this, such as the Best of MathOverflow thread. We could do more in this direction and this could have interesting repercussions. Vidit Nanda recently suggested that our front page still has too low signal to noise ratio to attract new experts in areas of need.
We are looking for fresh ideas. Ideally, such ideas would integrate well with the functionality of MathOverflow (and low burden on the MathOverflow crew). An interesting line of thought is to add more sophisticated editorial features and privileges in a similar fashion to the array of moderation features and privileges that users currently enjoy. Let's hash out some ideas here until we have some concrete feature requests to make.