Here’s a knob that needs to be held. The Griffin PowerMate ($60) allows for customizable programming of frequently used functions, such as scrolling, volume control, opening files, etc. The scrolling wheel/knob comes in handy for anyone who works within a certain program a lot, such as iTunes, video editing or RSS readers. It’s also Bluetooth compatible, enabling wireless connection to a computer. No ugly wires cluttering up a desk And hey, there’s a pretty blue light underneath. Even that can be customized.