Earlier this year Logitech announced the NuLOOQ Navigator (crazy name, cool device), a button/dial combo that’s designed to sit in your non-dominant hand (i.e. the one you aren’t mousing/drawing with) and provide quick access to tools, zooming, panning, and more. There are some brief video overviews on the product site, showing how you can bring up a little on-screen tool dial that’s context-aware (displaying options relevant to the app & tool you’re using at the moment).
Now they’ve made the product much more affordable (chopping the price to $79.99) and made the product compatible with Windows while adding support for a number of additional apps (iTunes, iMovie, etc.). These moves make the device much more of an impulse buy, and I hope it sells like hotcakes (er, Krispy Kremes, or Tickle Me Senseless Elmo, or whatever people are buying like mad these days).