Several years ago, I was on the verge of quitting anything due to computers due to severe carpal tunnel pain in my right hand. By sheer luck, I found out that my problem was the MOUSE (even though absolutely everyone told me it was the keyboard). I tried all the expensive split and wave keyboard and it wasn't getting better.
Then, one day, I had a wacky idea. I got a wireless mouse and put the mouse just SOUTH of the spacebar, slightly to the left of center. Imagine a line extending from F2 to D on a standard board. Then double that distance down and that's about where I put the mouse. It's pointed at a heading of about 285 degrees, that is, slightly North of due West. To reach the mouse, then, I ROTATE my right arm from the elbow about fifteen degrees leftward, mouse a bit, then get back to the board.
Along with this goes a posture where I am leaning WAY back in a chair, my forearms rest in front of me on the table / desk (Ferrari style ;-P), my elbow bones are JUST OFF the edge, and the keyboard is pushed about twelve inches inward from the edge. My arms NEVER slide, my wrists barely touch the table (that is the cure for my carpal tunnel RS). My right hand rotates just a little around a pivot point just a little upward from the elbow bone toward my hand. The mouse LIVES in between my hands, just under my left hand. You can see that this would be impossible with a wired mouse, because my left wrist would be on top of the wire, preventing normal movement.
Ok, this layout saved my job. It absolutely and totally cured the carpal tunnel
I will also occasionally use an Evoluent vertical mouse when I can't assume this race-car posture. It's a really great second place.
[EDIT] Needless to say, after finding this cure, I went back to completely ordinary IBM-layout rectangular boards, then went on a quest for better switches, finding cherry and Topre. The wave and split and jazz layouts did nothing for me.