I use cornflour mainly to make up hot chocolate mix. It's from Jamie Oliver, cornflour, icing sugar, Horlicks, cocoa powder, chopped dark chocolate (or chips), pinch of salt and cinnamon. Shake it all together in a giant kilner jar. Makes lovely hot chocolate. D1 has often made jars of it up for friends for Xmas with a bag of marshmallows and a couple of flakes.
But apart from that, surely it's just a cupboard staple along with baking powder etc. Things you don't have to buy that often because you only use small amounts, but always have in.