Kensington, thumbs up
I bought a Kensington Expert Mouse a little over a year ago as a New Year's gift to myself. It's a nice trackball; I left-click with my thumb, roll the ball with index and middle fingers and scroll using the ring with my ring finger. I can use it all day without getting soreness in my right hand and wrist and it “just works” with OSX and FreeBSD. I like it more than any other pointing device I've ever used. Recently the scroll ring started to stick and skip, not all the time, just often enough that it interfered with my concentration. This annoyed me enough that I dug out an old Logitech trackman that I never really liked but at the time was an improvement over a sore wrist from the mouse. The Logitech is not even in the same league as the Kensington.
The unit has a 5-year warranty, and should given the premium price, so I called up the toll-free number expecting a hassle. I was bristling for an argument that the unit needed replacement. I had my original receipt, the warranty card and most of its original packaging. There was no hassle. The service representative took my information, apologized and informed me that a replacement was being shipped and should be at my home in ten days. No need to send in the old unit, no problem at all. I didn't know what to think.
A week later, just as said, a new one was delivered. New, not refurbished, not restored. New. Original box and another 5-year warranty. Way to go Kensington! I'm now looking at their other warranteed products with a different eye, instead of asking myself “Who pays that?” I'm thinking, “Hmm. Maybe it's worth the price.” If they made a mechanical, buckling-spring keyboard I'd buy that in a second. Thumbs up.