An extremely popular use case for Redis' sorted sets is leaderboards. During the last GDC I was amazed how practically every game developer I talked with was using Redis just for that - here's the post I had published afterwards: <a href="http://redislabs.com/blog/the-top-3-game-changing-redis-use-cases" rel="nofollow">http://redislabs.com/blog/the-top-3-game-changing-redis-use-...</a>