We all have them. I certainly beleive they are curcial. To me the lift starts a few minutes before you touch the bar. We all know how important the mental aspect is, and physical rituals are a well linked part of that.
For me, I have several depending on the lift. Generally, if it's a lift on the floor I will go to the right side of the bar, squat down, grab the bar on either side of the plates and tap it with my forehead. I do the same for squats as well. I also slam my feet twice before big O lifts and I chalk my hands in generally the same fashion... block around the thumb, scoop of powder with the right to the left hand, rub it in, clap, and roll!
So what are yours? Any real peculiar ones?