How about, in addition to helping people track the movies they watch, you display information about which directors/actors/etc they seem to like best (based on the movies they have `liked', of course...)

Also, after clicking through about 50 movies on the `Discover Movies' page, I had `The Usual Suspects' show up about 15 times in a row on the page. Don't get me wrong, I love the movie, just figured I'd submit this particular behavior as a bug...:p