A friend of mine has set this up-
You join and every Friday at 3pm you get sent a link to the site and there's a still from a film, and the longer you take to guess it the less points you get, and the more clues you request the less points you get. There's an ongoing leaderboard.
Needless to say, the picture is usually fiendishly hard. If you're film-nerdy, it's great fun.