This changes the colour of the background depending on the day of the week! Just place this after the (/head tag) and before the (body) tag (which you will have to take out)
<?
$today = date("w");
$bgcolor = array(
"#FF0000", "#00FF00", "#0000FF", "#FFFF00",
"#FF00FF", "#00FFFF", "#FFFFFF"
);
?>
<body bgcolor="<?print("$bgcolor[$today]");?>">