Here is a tool that I have made that a I have really needed to get around making.

I forged this from a length of 5/8ths coil spring that I had to perform an upset on. An upset is basically heating a specific area of the work piece and then hammering the ends to force the material in on itself into a large knot that is larger in the actual cross section of the rest of the bar.

This tool is referred to as a "Holdfast" It is a tool that can be seen in wood working shops as well as the blacksmith shop for it is just that versatile. The tool is springy and has a long shaft that is driven into a hole either on the workbench or into the pritchel hole of the anvil. The way it is driven down over a piece of metal or wood causes the spring portion to flex and drive the shaft of it against the hole's inner wall.

This creates an incredibly strong way of clamping things, the material underneath refuses to budge and the only way to unclamp anything under the pad is to strike the back end of the hold fast with a hammer, this jars it upward and releases the spring's pressure.

This is an incredibly useful tool to me as a smith, because it means I can have something hold things in place for me while I cut it with a hot cut chisel, or perhaps use a fuller or butcher tool.