Have crossfire option specifically for people who are teamed up in clans. Also have it set so that clans can have their own personal home arena as well as a choice of symbol and color scheme for their character outfits. Also have a choice of whether to play a ranked or scrimmage match. Later on set it so that clans can spectate their clan matches or other players can spectate the ranked matches. Create a ladder showing the top guilds during off season and during certain times of the year (aka season) take top clans and enter them into a playoff tournament. Winners of the tournaments receive prizes, bragging rights and/or exclusive downloadable content for their outfits.
Maybe add an option of some sort of in-game clan recruitment or maybe a bulletin board option where clans can post their requirements, skill level and what classes they are looking for. Would make it alot easier to get a clan going then having to surf the forums.
Or...you could have an advertisement on the loading screens for the forums. That would simplify both of your wishes.
Hmmmmm...Skill level: good when not dicking around Classes looking for: A team that actually wants to scrim & needs an assassin That's me & what I need...but in all seriousness can you really see uber doing that for 360. Peeseers maybe. Nice idea though and I approve