Personally, the Netflix recommendation system usually returns things I like, and the little sidebar telling you why it recommendeded that particular flick based on your ratings of other movies is helpful. I know when I rate things like TVONDVD highly simply because I like the show, I get bombarded with recommendations for crap TV on DVD, but that's something I can live with. For me the system works fairly well.

Certainly better than Amazon's recommendations I find. There are too many things that Amazon sells for them to make a decent go of recommending things to you.

An example: Just because I buy a Gamecube game, it doesn't mean I emphatically must have the Resident Evil Gamecube controller!!! Jeez.