I tried this out and loved it, and raved about it, and I've gotten a lot of other people hooked on it too. I'm on a no-sugar diet so I've added other things.
We've added:
-strawberries
-peaches
-mexican vanilla
-1 tsp each cinnamon, vanilla, and cocoa powder (to 4 bananas)

We've discovered:
-peel the bananas before freezing
-break the bananas into chunks before freezing so your food processor doesn't leap out of the kitchen