If you need to need to heat water without a kettle or make a grilled cheese sandwich without a kitchen, you can use most irons as a hotplate. Simply find a way to secure the iron upside down, turn it on, and wait for the flat metal surface to heat up.
Science and mathematics blog Topologic Oceans shows us how to clamp a piece of wood to a bench and use it as a secure holder for the upside-down iron. Just make sure that whatever you heat won't be ruined by a hot metal surface or otherwise cause a fire hazard. For an even sneakier take on the same concept, try cooking your bacon with an iron.