The Two Half-hitches
This knot is really just an extension of the half-hitch. Unlike the single half-hitch, this knot will hold a reasonable load when tied properly. An extremely useful and practical knot.
Knot Video: How to Tie the Two Half-hitches Knot
Knot Tying Instructions
Step 1 - Tie a garden variety half-hitch.
Step 2 - Tie another half-hitch right in front of it, with the same orientation as the first half-hitch (counter-clockwise in this case).
Step 3 - Pull it tight!