Parallax scrolling is a technique that the background images move by the camera slower than foreground images, which can give the viewer a 3D/motion illusion. It was firstly used in the video game and started to appear in some fancy web design works recently. If your website is already awesome, adding one extra parallax effect would easily give visitors a bigger impression. To make your life easier, there are some excellent plugins and tutorials to get started. They are well written and documented and you might just add a few your own pictures and automatically have a parallax page.