Ever week my organic box includes a bunch of bananas. Every week I do not eat them all before the point at which I consider bananas too ripe to be edible. (Note that this is the same point at which most people begin to consider bananas sufficiently ripe as to be edible.)
So what I do with them is break them up into small pieces and throw them in a plastic contain with 1/3 of a cup of milk per banana and toss them in the freezer. When that's frozen together, I bring it out and add some splenda (though sugar would work just as well for people who aren't trying to lose weight) and throw it all in the food processor (though, blender would work better for those who, you know, have one) until it's creamy.
Insta-banana milkshare, practically guilt free since it's made of things like bananas and skim milk and not things like ice cream.