Here's a design from the depths of time

(i.e. the back of my 10th grade mathbook)

   

These are just some knots I found somewhere online, and I really liked them.

(Don't ask me where I got them, because frankly, I don't really remember...but if you know, let me know and I'll give credit where credit's due.)

And now another look at one of my own (it's my favorite)

Some more designs by other people:

Another one I designed myself

(I cleaned it up with MS Paint)

 

Some more of my own pics:

 

And finally, one last trio drawn by someone else