A friend and I were talking about mini games in MMOs and how the perfect set up for such a thing would be a traveling circus. Each week it could go from major city to major city.
Not only could there be huge tents with really cool stuff to sit down to see(help with friends gathering/roleplaying), but there can be fields of smaller tents with different challenges for the players. There can be race tracks, shooting galleries, mazes, riddles, jumping games, etc.
All of these could be a giant money sink as well. You spend gold to do these activities and you can earn tickets or win a prize or whatever.
I think this would be a nice distraction from the everyday questing and killing.
Another idea would be to have a zoo in some of the larger cities. This could be another really cool place for friends to gather and role play, not to mention if they really did it up right, would be a cool place to see.