How Yelp deals with everybody getting four stars (on average)
venturebeat.com
venturebeat.com
I'd argue that this should be how any community-based rating site should work from the start. "Best" isn't objective or one-dimensional. Netflix doesn't expect every customer to rent the same top ten movies. Amazon doesn't try to recommend the same book to everyone (at least, now that Harry Potter is over)...
My problem (and other's) with yelp is their discovery system is muddled in with their revenue model. That is you can't really trust the algorithm because they're also putting restaurants who paid at the top. So it no longer is a user revenue but an Adword. Not cool.