Wanted a place to keep track of what movies I was watching, when and who I was watching them with, and then be able to recall them later.
For instance: Recent movies watched http://movief.ly/users/adamfortuna/viewings
Movies first seen in 2009 http://movief.ly/users/adamfortuna/lists/first-seen-in-2009
Never went beyond the 'scratch my own itch' stage, but gomiso seems to like the idea of checking in to TV/movies.
For instance -- What're my girlfriends favorite movies that I've never seen? Or What are my friends favorite movies of all time (that I have seen or haven't seen)? In the end it's all about keeping track of what you've seen, and helping decide what you should see next though, so it might have Netflix integration so I don't have to reinvent the recommendation wheel either. What movies you'll like is only half the equation though -- the other half is what people you know are actually watching!