I see there's a page about this on the site: http://www.fieggen.com/shoelace/grannyknot.htm
Until, at the ripe old age of 32, when a friend tipped me about Ian's shoelace site, and I finally learned how to tie my shoelaces properly.
It's a great example of not knowing what you don't know, because shoelaces, right?
To me it's fascinating as it's something taught at a very early age, something used nearly every day, yet something a lot people seem to do "wrong" (inefficiently) by habit or ignorance.
But now my kids know and can suffer less unties, so that's good.
Similar thing for me, the "use a food packet as a bowl" trick (eg for crisps/potatoe chips).