Deviantart's code is
Code:
<link href="http://i.deviantart.com/icons/favicon.png" rel="shortcut icon"/>
(with
http://i.deviantart.com/icons/favicon.png being the URL of the image). You should include this element in the HEAD section of your HTML document if you want to use the icon. IE does not support PNG favicons, so you'll need to find something which can save to the .ico format. Try
http://www.winterdrache.de/freeware/png2ico/
Mozilla/Firefox support the .png icons, so if you want to target it to those browsers, you can just use a normal image. They do, however, require the link element (code above) to be used in your page. Only IE checks for favicon.ico in the root directory.
IE is also pretty unstable with it's favicon system, so you can add one, but it might not show up every time.