What are rack lockouts and how do I do them? I hear they're really good for triceps.
They are good for you lock out (if your a powerlifter). They are done in the power rack at the top range of your bench.
There was a variation posted in an Ian King article (I think). Instead of doing them from a bench position, you set the bar just over your head while seated in the power rack. Then lift from there. I tried them, they're great. But you have to lift heavy.