This nifty infographic (from The Art of Manliness) reveals how to measure the remaining daylight with just the fingers on our hand:
1: Face the sun and extend your arm in front of you. Have your palm face toward you and your fingers parallel to the horizon.
2: Position your index finger so it rests just below the sun and your pinky finger is parallel to the edge of the horizon.
3: Count the number of fingers it takes to reach from the sun to the horizon. Each ascending finger is 15 minutes until the sun sets.
4: If space allows, line up your other hand directly below and continue counting. Each hand represents roughly 60 minutes.