A totally different direction from the Kinesis, but this has kept me happy for the past 5 years: http://www.pckeyboard.com/page/product/96U1114

There are trackball buttons on the top of the keyboard. When using it, my right hand curls around the corner and my thumb is over the trackball. I have the 2nd mouse button set to scroll-lock, and scrolling up and down web pages and through terminal histories never felt better.