This generates perfect circular motion centered around the original position of the layer.

This expression will allow you to zoom a camera in After Effects using real-world focal length values.

This Expression causes one gear to rotate at the proper speed when a second gear next to it is
rotated, so that the two gears stay meshed with each other.
by Fred Lewis

This is a variation on the pendulum expression.

Keyframes were applied to Jack's position at frames 0 and 1 to move him out of the box

This is an expression you can use to generate a decaying pendulum motion.
by Dan Ebbert

Creates an oscillating motion between two specified values over a specified period of time
(in seconds).

Creates an oscillating motion between two specified 2-dimensional positions over a specified
period of time (in seconds).