Netflix does. By cross referencing your likes and dislikes against those of your fellow Netflix members, the company is able to create a meta rating system, in which the score you see for a movie is your own. You see that score because that's how much Netflix thinks you'll like it, based on how similar people liked it.
This is the only good way of going about this method. The trick is, it's easy to do this with movies, but much more difficult with product ratings and the like. Maybe this is an opportunity for someone to build something on top of Facebook or Amazon.
Pandora does something similar. They only have "like" and "dislike" rating. If you like a song they look at other users who liked that song and try to find more songs/bands from the people with your taste. And the other way around for dislike i guess.
It works exceptionally well. You just listen to the stream of incoming songs, you never pick songs yourself. After a good song you click like, after a mediocre song you keep listening, during a bad song you click skip. After a few days you will only get good songs! (with a few exceptions of course) It's like magic, i can't even count how many new bands i found through pandora without any effort.
Is Netflix really the only site which does this nearly-braindead machine learning approach?
Once you realize that people have different tastes and you know someone's preferences that is the obvious solution. Or is the process of crawling through that much statistical data that expensive that it can only be offered to paying subscribers?
The more accurate you want to get, the more computationally expensive. Netflix actually did a contest with a million dollar prize to the team that could come up with the most accurate rating prediction algorithm. In the end, the million dollar algorithm was too expensive to implement, so they never ended up using it.
rateyourmusic.com sort of has this, but it's not in the default view. You have to go to an album and click a "View my suggested rating" button, then it whirs for a few seconds before giving you an average of ratings from users with similar taste. It would be much more useful to browse the whole site with those ratings showing, but I get the feeling it's a computationally expensive feature.
Netflix does. By cross referencing your likes and dislikes against those of your fellow Netflix members, the company is able to create a meta rating system, in which the score you see for a movie is your own. You see that score because that's how much Netflix thinks you'll like it, based on how similar people liked it.
This is the only good way of going about this method. The trick is, it's easy to do this with movies, but much more difficult with product ratings and the like. Maybe this is an opportunity for someone to build something on top of Facebook or Amazon.