A chestpod, as you probably already figured out from the picture below, is a kind of monopd that you rest against your own body during a shoot. It gives you the freedom of moving around without worrying about where to put the camera down. It is specially designed for instances when you have to keep the camera stable for a few seconds and cannot hand hold it but do not have enough or proper space to carry around a monopod in your hands. Imagine yourself taking a few night shots lying down on your back. You can just easily lie down with camera balancing on your chest and the LCD right in front of your eyes while you compose the shot.