There have been many attempts at this kind of thing before, e.g RecommendBox. The trouble is it requires active participation. If I want to share the love I'm far more likely to shout out on facebook or twitter. Perhaps what you need to do is scrape your friends/followers feeds for their likes?
Also - how are you going to stop spam? THe first wibbler I checked was this: http://wibba.com/thisiskewl/