I try and always be as careful as possible. I have had pieces of wood thrown back at me a couple times by the table saw and I have had pieces of wood "explode" on the lathe that parts of hit me. I always wear eye protection, stand out of the line of fire, all the normal things and none of that has ever scared me or made me concernd any. There is one thing that scared me, and now I ALWAYS check before starting a project and every few cuts. That is the carbide teeth on my saw blades. I was working on a project and about half way through when something caught my eye on the tablesaw. I looked closer and found a missing tooth from my blade. I rolled it over and found 3 more teeth missing from it. Where the hell did they go? I even took my shirt and pants off in the shop and checked myself. No holes or marks, but I am still leary of my carbide toothed blades and keep a close eye on thier condition. So, what scares you the most in your shop?