I've started using a Command Creature spell recently, and it's great fun and very useful in areas with lots of enemies. They'll all slaughter each other until there is only one left. Watching two Storm Atronachs go at it with each other is interesting, since their shock bursts have no effect on the other...
I made a Command Creature up to level 25 for 10 seconds, but I think the time could be less. It seems that as soon as you cast the spell on some creature, it will fight others in the area until it's dead, no matter how long the battle takes.
Just created a similar Command Humanoid spell, but haven't tried it yet.
Anyone else use Command spells much?