The Griffin Powermate nailed it: a simple, just-works USB rotary knob perfect for scrolling, zooming documents and playing Arkanoid. And it looked great, too, with brushed-metal bodywork and a glowing LED ring. But it was discontinued years ago and the required software hasn't been updated. James Lockman has written drivers enabling these ancient gadgets to work perfectly on modern Macs. When it was released, it was intended to assist video and audio production by adding a scrollable knob to your desktop. Of course, modern controllers exist that offer many more literal bells and whistles, but there is something… quaint… about this early device. The PowerMate acts as a scroll control, so if the active window or control has a scroll option, turning the dial will scroll the window or increase/decrease selected value. You can reverse the scroll direction if you don't like the default scroll direction. The PowerMate also acts as a mouse button. A momentary push of the button acts as a mouse click.…