I just picked up a Griffin PowerMate knob (aluminum) and find the device to be fantastic and quite useful. In case people don't know, it's a solid-state knob that has a click-and-dial feature that can be programmed to do any key commands or preset commands you choose. I've used some presets and created my own -- for example, when i click it in the finder (global), it opens iTunes. Within iTunes, I control volume and track selection. Safari works for scrolling and for moving among pages. Anyone else find this device highly useful? Anyone care to share tips on usage? Best.