http://www.griffintechnology.com/products/powermate/ Nothing more than a simple yet elegant 'button' for your desktop that wires into your machine via USB. It feels very much like a tuning wheel on a very nice HiFi stereo tuner, with a very smooth action and easy one-finger manipulation. The button works for roll left, roll right, push, push & hold, push & hold left, & push & hold right. Each position can be customized to do a specific function either system-wide, or specific to whatever program your working in at the time. Customization is easy with a straightforward Prefs Pane for the system preferences. Available in brushed aluminum finish (what I got to match my G5) or in a powdercoated black finish. Both are currently US$39.99. I got this thing for my birthday from my mother-in-law. I have an online birthday/christmas wish list that I did a year or so ago so that I could remember what I wanted throughout the year when people asked me closer to time. She found that, thought the price was right, and ordered. When she gave it to me and I unwrapped it, she said "I can't believe I gave you a knob for your birthday." She was right, and at the time I didn't really know what the extent of the knob was - just that I thought it looked cool with the glowing blue light underneath. Of all the functions that this thing is great for, the coolest of the bunch is in Photoshop, if you're a power-user like me. Being able to have it change brush sizes on the fly with a simple twist of the knob is just about the coolest thing since sliced bread. Combine that with the power of a pressure-sensitive pen tool, and you'll never want to use Photoshop any other way again. ***** con - the attached USB cord is too short for use, unless your machine is on your desktop next to it (mine isn't) - but they're nice enough to include a USB extension cable for that very reason.