Also, for table saws, there's SawStop. This is expensive, about $1500 for their table saws (made in USA), but protects you from lost fingers. Table saws cut off about 4,000 fingers a years in the US. SawStop has a system which detects a touch to the blade by anything conductive (such as a finger) and fires an explosive charge which jams a stop into the blade, stopping it in half a tooth of rotation. This costs you about $150. TechShop has these, and they get about two emergency stops a year.