Gravatar API example

<?php
function getGravatarURL($email, $size = 80) {
    $grav_url = "http://www.gravatar.com/avatar/" . md5( strtolower( trim( $email ) ) ) . "?s=" . $size;
    return $grav_url;
}
?>
<img src="<?php echo getGravatarURL('[email protected]', $size = 200)  ?>" alt="Gravatar" />