Mosaic jQuery Plugin automatically generates sliding boxes & captions. It allows slide & fade animations with custom directions. It preloads images within boxes. It is very lightweight at ~2kb (minified).

Implementation is fairly easy, they have provided a number of sample configurations in the downloadable file. It operates with two panels – an overlay and a backdrop. The content in the overlay gets repositioned according to the options that you provide.

Requirements: jQuery Framework
Demo: http://buildinternet.com/project/mosaic/
License: MIT, GPL License