Rating of forum responses

You know what would be the most awesome of a feature to add to this web site? The ability to rate the response a person gives to a question in a forum. I have seen this on other web sites.

The problem I keep running into is you ask a question and get 8 responses all talking about something other than the question asked. In the end the thread gets tired and people move on, yet the question is never answered.

If users could get some rating as to the quality of their answer, maybe this could change for the better.

Thanks for the consideration.