Hazards/Equipment: Elemental Hazards
Dragon Magazine #347 has a very interesting article called Elemental Hazards: An Exploration of the Inner Planes. The article describes various unique hazards, materials, and phenomena that can be encountered on the elemental planes. As a person who adores everything elemental-related, I must convert the article to GURPS. Such features make the Inner Planes feel very different and unique compared to the Material Plane. I've always entertained the idea of running a game set predominantly on an elemental plane, but it would probably be impossible to find players for that.