Scroll down most of the way on the RHP home page and look along the right side of the page.
There is the "blitz chess" link which is not rated and there's also a link to uchess which has ratings for speed games.
Or you can just access them directly:
http://www.redhotpawn.com/blitz/blitzchess.php
http://www.uchess.com
See you there 🙂