I think it would be a great boon to teamwork and coordination in this game to give us a Teamate winow in the interface.  It could display useful information on your teamates such as health/mana, level, and gold.  Currenty if you aren't in the same lane with them you will have no idea how your teamates are performing or what they are doing.  This would be helpful also in coordinating citidel upgrades and most importantly helping new players.  You could see them with a certain amount of health and tell them to run, or see them with a certain amount of gold and ask them to buy certain upgrades or gear for themselves.  Most importantly in more competitive games it would be really helpful so if you are playing a demi with say a shield, heal, absorb or other team skill you could know when you might be most needed.