Parallax scrolling is hot right now. First popularized by Nike, the number of site’s featuring the dynamic technique has exploded.
The parallax effect, or parallax scrolling, in web design features layered images that move at different speeds, creating the illusion of depth as you scroll down the page, kind of like a faux-3D effect. Usually the background moves slower than the foreground. The technique uses scrolling to reveal new content and works similar to one-page sites where all the content is on a single page.