http://www.fieggen.com/shoelace/secureknot.htm

Link above should take you to Ian's Secure Shoelace Knot. I have been using this knot for a couple of years now and it has completly solved my chronic problem of shoelaces becoming untied.

Took me a while to change my lifelong method for tieing my shoes but it was well worth it. It is the only knot that now use. I can tie it as fast as my old knot and it comes untied with a pull of the laces, just like the standard shoe tying knot.