The Xelerator, Perfect Circle, Wrist Snapper and the Spin Right.
Once the pitcher learns the basic pitching mechanics and can pitch somewhat consistently, coaches will start to teach them the movement pitches. In order pitch the movement pitches one has to learn how make the ball spin. The Spin Right is a good tool to get them accustomed to the feeling associated with spin enhancement. I found that the ball itself can also be used for this purpose. I learned to visualize the spin on the ball when the seams were blackened with a felt marker. You can also place a strand of black tape around the ball. I personally found it easier to interpret what I saw with the seams blacked out.