jParallax is jQuery plugin that creates a parallax effect by turning a list into a viewport. The list elements are displayed as layers that are absolutely positioned and move in response to the mouse with varying dimensions.
The easiest way to create a Parallax effect is to use images of different sizes that are larger than the size of the viewport. Larger images move faster and appear closer, while smaller images will appear further away. The dimensions of each image are defined with CSS.
The plugin has various options to customise the effects. It is well documented and contains many examples.