I think a pretty interesting and useful idea for the site would be for it to allow you to set up a team of people (each picking their classes in this) and search/join a game together with those slots open. For example you could set up a 6v6 team and only have a Scout, Pocket, Medic and Demo and you could join a server with those class slots open.
I just think this would be a good idea and would make it easier to join with a team of friends.