If you like the site's colour changing buttons, then head over to here and have a read of Jonathan Snook's blog. Here he outlines the concept, like using sprites for mouseovers, of scrolling the background which has been used to great effect here and on Sealeys.

To work with this effect you do need the usual jQuery library and the background scrolling plugin.

The images on top are layered and use the builtin jQuery .fadeIn() and .fadeOut().