Ambient background color changer (tweetable).
Move your mouse over the page and the background changes smoothly from green to blue.
You can easily customize the colors by editing the last part of to code...
document.onmousemove = function(e){ // use the mouse event
x=e.clientX; // X-pos and ..
y=e.clientY; // Y-pos of the moues on the browser screen
document.body.style.backgroundColor = "#1040"+ // change to "#5000" and look what happens ^^
Math.ceil(y/7+x/9).toString(16) // is important for the smooth change
