If you're changing planes or trains but have a longer stopover between services, you often want to explore the surrounding area but aren't sure how far you'll be able to go. Webapp Cartoo uses Google Maps to predict how far you can travel from a given point in a specific window of time.
In my example image above, I've given Cartoo the address of Grand Central Station in NYC with a two-hour stopover. The resulting area in green above is how far I can walk from that point and make it back within two hours.
Since this is merely an extrapolation of Google Maps, you'll probably want to use the service as an estimate and allow a 15-minute buffer to avoid potentially missing your connection. With that in mind, it's a handy little webapp. Unlike rival Mapnificent, which only covers public transport, Cartoo focuses on walking and driving.