The Forehand Pendulum Serve has the racket move in the motion of a clock pendulum, circling down and forward. This is a very effective service type because with slight adjustments it can make underspin, sidespin, topspin or no-spin, while the stroke will look quite similar. This is good for disguising the spin on your service.
This serve is also very versatile in that you can do a large variety of serves from that starting point, and the opponent won't know what to expect.
Shakehand players often change the grip on the racket when performing the forehand pendulum serves, then immediately change back to prepare for the rally.
These are sub-pages of the Forehand Pendulum Serve page (a child in the hiararchy).