I use a diamond knot on loop lanyards. Not very goot strength wise, but looks real cool, and functions sufficiently for a lanyard. For straight lanyards, I prefer a simple braid. You can braid a single piece of cord without cutting with a bit of though, and have a loop and a free end at each end of the braid. Hangmans nooses are rather easy. just make a loop, with a free end at both sides, one (your running end) sufficiently longer than the other. Begin wraping that one under the loop on it's side, and go till you run out of rope. Stick the last remaining bit through the loop on the far side, and pull that loop down using the loop on the end you began with. That first loop then becomes your noose part, and can be tightened/loosened via the standing end (The free end you did not wrap with). Legend has it that at 13 wraps this knot locks on tightening. Legend was wrong. Legend also has it that this knot is illegal. Legend is also wrong, in most places I know. Hanging someone with this knot may be illegal though. If you wish to simulate someone hanging, you can make a similar knot, but with an extra fold, so that one end has two loops, and one has two ends and a loop. Wrap the same, and pass the running end through both loops on the side it ends up at. Tightening will be more work. Tie this running end to a harness (preferably a chest harness rig) and place a loop of similar rope around the 'victims' neck, tied with a light string to just below the noose wraps. This will do a rather convincing job of looking like the rope is hanign said person, while letting him fall free should the harness/rope fail.
Well, I guess that ran a little off topic...
Stryver