I visit IMDb.com from time to time, usually after a conversation involving some movie somebody has seen, or a TV show. It's an awesome site. But there's one thing that (as far as I know; it could be one of those "Need to register" deals) I think would be an awesome feature. What if it let you pick all the movies you've seen (through a simple Netflix-style interface) so that when you look up a name on the site, you can see what movies they've been in that you've seen? I know it might take a lot of time to list all the movies; it would have to be something really easy to do and would register it every time you checked a box or something.
This wouldn't have to involve some fancy algorithm, like how Netflix recommends movies for you and stuff. It would just be a neat way to see what movies you've watched that have a certain star in it. Wouldn't that be cool? OK, maybe not. But still, haven't you ever looked up a name and thought "What other movie did I see him in?" Eh? I know you have.
Remember to include me on the patent/copyright.