The header picture on this website changes based on the time of day. You can change your website photo automagically throughout the day too. It isn’t very hard with a few photos and a bit of PHP. This is similar to what Google does on their customized home pages.

<?php
// This neat piece of code changes the header image
// based on the the time of day, EST.
date_default_timezone_set("America/New_York");
$hour = date("G");
if ($hour < 6){
$pic = "twentyfour.jpg";
}elseif ($hour < 9){
$pic = "six.jpg";
}elseif ($hour < 12){
$pic = "nine.jpg";
}elseif ($hour < 15){
$pic = "twelve.jpg";
}elseif ($hour < 18){
$pic = "fifteen.jpg";
}elseif ($hour < 21){
$pic = "eighteen.jpg";
}elseif ($hour < 24){
$pic = "twentyone.jpg";
}
?>
<img src="./images/<?php echo $pic; ?>"/>