I would say the way pioneered by http://www.StackOverflow.com is the best way, where responses are voted for, but you can only vote for a response if you have "credibility".

So then the person who finds the question later has a good indication of which the correct responses. I have found this works very well, and in fact have yet to find a question posted on Stackoverflow, which has voted answers, that didn't work as per the most voted answer!

They have a api called StackExchange which allows anyone to set up the same type of site, perhaps that should be looked into...