I use a variant on a fishermans knot I've never seen anywhere else. It's tied on my tankard as a belt loop, and various other, less important things as well

If you tie a fishermans knot, using the two ends of a piece of rope, you have a loop. If you tie the two halves of the knot round the other side of the loop as you tie it*, you have two adjustable loops, which should be just as strong as a standard fishermans. I find it most useful tied as a double fishermans, so the rope will only move under real effort.


* if you want to know more, PM me, and I'll explain somehow...