Since contributor Ryan Lewandowski apparently hasn’t used the following item personally, I can’t include it as a regular Cool Tool, but the online promotional video is so compelling, I encourage you to check it out at Sawstop.
The SawStop is a table (circular) saw that supposedly stops itself if you touch it with your finger. The video uses a hot dog as a finger substitute, which is marred by only a shallow nick before the saw arrests and retracts with a bang. According to the “how it works” section of the site, the safety system is electronically actuated by the capacitance of the human body. Since I have always felt uneasy using table saws, this innovation is of great personal interest. If anyone has used it, I’d love to hear about your experience.