The Marlinspike hitch is my favorite :) If you stick anything functioning as a marlinspike in there (stick, screwdriver, etc.), you get a great handle for pulling in tension. If you put a hook in there, you have a hitch onto the hook that can be released by slipping it off (and the whole knot collapses in on itself). If you stick the tag end one way instead, you end up with a great stopper knot (Oysterman’s Stopper Knot) that is triple the diameter of the cordage. If you stick the tag end in another way, you end up a Bowline—and it’s a whole lot faster tying it than the “rabbit-around-the-tree” method.