How to Add Website Favicons to Your WordPress Comments in 5 Minutes

There's a url you can access on Google.com that will give you the favicon for the requested website.

http://www.google.com/s2/favicons?domain=www.highmac.com

So to use this in your theme you can place a little function in functions.php:

function bm_getFavion ($url = '') {
	if ($url != '') {
		$url = parse_url($url);
	}
	$url = 'http://www.google.com/s2/favicons?domain=' . $url['host'];
	return $url;
}

[Binary Moon: Add Website Favicons to Your WordPress Comments in 5 Minutes]