Have you seen those bicycle utility things that are popping up all over? They're a load of useful tools mounted to a post: Pump, nut tighteners, screwdriver, rack etc.
My invention is a version aimed at humans. A post in every highstreet with essential tools for the public to use when needed. I'm thinking of:
Nail clippers
Nail file
Hairbrush
Shoehorn
What else would be useful? I thought about one of those foot shaving machines but I think it would be better to stick with non-powered things.