I like knots; there, I've said it. My father-in-law, a navy man, got me interested in knots a while back and bought me my first knot book and I've had a fascination with them ever since. But, here's my secret...I can't remember how to make a knot to save my life. Every time I want to make a knot I have to reference my book and, no matter how many times I make the knot, the next day that knot-know-how slips my mind. Most knots serve a utilitarian purpose, but can be beautiful at the same time. The Monkey's Fist knot is an example of this duality of being. It can act as great ballast (i.e.: doorstop) and, also, look pretty cool.
Design Sponge posted a how-to guide illustrating an example of a homemade Monkey's Fist knot and it's expensive store bought variety. I can tell you that I referenced this site in making my knots and the total cost was about $6 for 2 fists compared to $40 in a store.