The way I used to tie my shoelaces, they would come undone every few minutes. So much that I just wore them untied a lot of times. As usual, the internet comes to the rescue and I found Ian's secure knot. I've been tying my shoelaces like that for a couple of weeks now, and they haven't come undone so far!
Ian has plenty more stuff about shoelaces at Ian's shoelace site. He may have just saved me from an inglorious death of tripping over my own shoelaces.