I am already thinking of doing some cake for work. You can use banana for the icing as well - just beat the banana with icing sugar and some lemon, and it gives a banana-flavoured soft icing.

The other thing I use banana in is porridge, it mixes through and adds flavour and sweetness. I'm not a fan of smoothies though, so limited use there. I might put bananas and custard on the menu for dessert tonight too.