[mckoss]

I think you'll find lots of attempts at ths problem. We tried to do this with data from Faves.com, our social bookmarking service. In the end we shut down our public recommendation service because we couldn't keep up with the spammers.

Any recommendation engine is a honeypot for web marketing types. I love the concept, but the scalable execution is very hard. I think the best sites approach this by engaging a motivated community, like HN, Reddit, and the original Digg. You need some zealous moderators to keep the spam at bay.