Kwicks, the sliding elements effect which became popular with the old MooTools page, has a slick jQuery version named “Kwicks For jQuery“.

The plugin accepts a flexible markup where a container wraps the sliding panels (can be an unordered list,  a <div> wrappping other <div>s , etc.).

Kwicks For jQuery

It has options for customization including the size, max-min width of the panels, margin between them, duration and easing for the effect and the behavior to be triggered for the effect.

Also, Kwicks can work both horizontally + vertically and it has an API for interacting with the elements and the effect.