The NFL hot seat is a vague concept. For some, it simply means they're aware that they need to do a better job of what they do. For others, it means they’re melting away in Dr. Evil’s volcano of liquid hot magma due to failed performances.
It seems as though at any point of any given season, every team has at least one player on the hot seat. It might be a coach or a GM, or it might be a star player.
Regardless, NFL fanbases and media love to find areas that need improvement. In order to make those improvements, it starts with the people responsible for those areas.
This slideshow discusses who has the hottest seat of every NFL team, and, naturally, some of those seats are hotter than others.