I have the MS Optical Trackball that you roll with your thumb. You roll the mousewheel with your middle finger. It also has the Forward and Backwards buttons on the sides. . Really like it, can't see using anything else.
BTW, I added mousewheel support for zooming in my $80 apps. Users love it. It and another feature were copied by a much larger company in their $40,000 app, right after they sicced their lawyers on me. Gotta love business ... NOT! Anyway, I'm looking into adding support for the Forward and Backward buttons once I figure out which resulting function makes the most sense.
Me too. I use the Trackball Explorer at home, the Trackball Optical at work. Personally, I prefer the Explorer, but I prefer them both to a mouse. Ditto my natural-style keyboard; it's another of those things that once you get used to it, you never want to go back.