Install and Settings for Zajax – Ajax navigation for WordPress. http://www.scriptsmashup.com/product/zajax-ajax-navigation-plugin-for-wordpress
Zajax is a WordPress plugin who add ajax navigation to your WordPress website. One of the strong and unique advantage from using Zajax is the page preloading feature on mouse hover, Some page will load on a blink of an eye. It will wait 100 millisecond on mouse hover before preloading the page to not overload your server.
Demo with full features: http://podzic.com/
Demo 2 with full features: http://reveilletoi.com/