A Clan Idea
Looking over Joystiq’s final word on the Fall Update, and seeing that clans are still nowhere to be found, it seems as though the Friends of Friends option could be used to gin up a somewhat functional compromise.
By creating a new Silver Account on your own box named (Let’s Say) Team Inferno, and and using this new dummy account’s hundred-man friend’s list as your clan roster, you can with a single invite get access to a well-groomed list of guys that is essentially tuned for this purpose. It’s not perfect, it’s not complete, and without Group Voice Chat it’s even less so. But it’s something I could see myself using.