Some of the Carribean airports don't have taxiways, so you have to make a U-turn to taxi back to the terminal. Also, made a U-turn in PHL last March... we had been holding because of wx delays, then the crew was about to expire for the day, so we taxied down the runway to go to the terminal, but then the wx cleared and the crew decided to fly it, and did a u-turn to get back to the end of the runway for take-off.