I was first introduced to these when au pairing in France as a gel - way back.
Now, the French have a very laid back attitude to making cakes, and the lady of the house used a chocolate cake recipe involving melted chocolate She would mix through with the stick blender to get the lumps out of the flour.
I use one for lots of things, too, these days - the nice thing is they fit into a coffee mug and can be used to whip up one single egg for brushing the tops of pies. I even stir my cocoa with it! I think I got it free with coupons from somewhere.