Exact Time

This is a silly phone app that shows you the exact time of your location from UTC based on your longitude. The floor and ceiling buttons show you your time zones on either side. Note that in the screenshot, you can see I live over 28 minutes away from the timezone line where my "time" is set.

This way, you know exactly what time you're at from UTC regardless of what the timezone says. It updates every minute, so as you travel you gain or lose seconds depending on your direction.