Geo Stock

This is a simple app that allows you to record your current location with just a double tap on the screen.
If you see a building of interest outside the window of your car or train, you can quickly record its location with this app and look it up later on a map. That place might be a wonderful spot that no one knows about yet, and it doesn't show up in any search. If that place piques your interest, you've got your plans for the next holiday.
*If there's an iPhone paired nearby, you can also record location information with the Apple Watch version of the app.