These holders are great as a pedestal for displaying your flies, but are also very handy on the stream for holding small flies while you thread your tippet. They can be used as an aid in tying a clinch knot: Use the tool to hold the fly at the back of the bend, thread your tippet, and spin the tool - all that's left is to pass the tag end through the loop near the eye.
These are a great companion to our Fly Tyers Boxes.