Flickchart.com might be my new favourite past time. The concept is simple: choose which of the two movies presented to you is better than the other. As each movie is rated, a real-time list of the movies you've seen and their position in said list is formed.
The concept is so simple that I've found myself giving into the "just one more" mentality to find that an hour (or more) had disappeared.
The nicest thing for me is the way the designers took a different approach from the standard footer you normally see. Instead of a uniform row of links, the navigation is treated as though it's the credits on one of the very movie posters you select on the site.
Although navigation should always be immediately identifiable as such I think that this still works in the confines of this site and the low priority that footer information represents to the user.