Parking in busy places...
So you've never done three laps of town trying to find a space? If the data is available, it can be stuck into an app. Whether the final use is helping you to find somewhere to park or letting you check online before you leave to see how busy the shops are going to be, I'd say that's a useful bit of data.
There's plenty more inventions of the past that have seemed useless at the time, but turned into something we find critical now.
"I think there is a world market for maybe five computers."
- Thomas Watson, chairman of IBM, 1943.
"But what ... is it good for?"
- Engineer at the Advanced Computing Systems Division of IBM, 1968, commenting on the microchip.
And just in the interest of not only picking on IBM:
" There is no reason anyone would want a computer in their home."
- Ken Olson, president, chairman and founder of Digital Equipment Corp., 1977.