With link code:
<a href='page.php?color=blue'>Make it Blue</a>
page.php includes:
if ( isset($_GET['color']) && !empty($_GET['color'] )
{
setcookie("color", $_GET['color'], time()+(60*60*24*365), "/", "", 0);
}
if ( isset($_COOKIE['color']) && !empty($_COOKIE['color']) )
{
$GLOBALS['color'] = $_COOKIE['color'];
}
else if ( isset($_GET['color']) && !empty($_GET['color']) )
{
$GLOBALS['color'] = $_GET['color'];
}
Basic idea...build on it.