I used to use Last.fm a lot for music recommendations and it was glorious. I discovered so many bands through that that I wouldn't have otherwise.
Likewise, a lot of my favourite films were found through LoveFilm's recommendation algorithm, and then Amazon started branding it more and more and the recommended list became a giant ad (So, it looks like you loved this Nordic horror film, why don't you watch Sex and the City 2?).
Can anyone recommend anything that... recommends?
Moon - "This is the best recipe in the history of recipes forever."