Avoiding carpal tunnel / repetitive stress injuries
adrianwaj: My solution was to place a standard building sized block of wood measured to the length of my  standard keyboard under the keyboard so the nearest edge of the keyboard sits up on the block, and the furthest edge of the keyboard sits on the table as usual. This way, the wrists can rest on the flat upside section of the wood with the fingers then drooping over onto the angulated keyboard. It's meant to simulate how your arms and wrists feel when you hang them down freely - no flexion of the wrists up or down, and relaxed.Similarly, place a thick book near your mouse for your wrist to wrest upon, leaving your palm to drop onto the mouse which slides on the pad that sits on table. For me, smaller mice are better that can be moved with just the fingers and highly sensitized.This solved the RSI in my forearms.Note: The wood block must be the correct size so that the keyboard slants neither too high nor too low, and that the forearms do not touch.I use: '2x4 (pronounced "two by four"), but few people realize that the actual height and width of a 2x4 is really somewhere close to 1 1/2" x 3 1/2"'
http://woodworking.about.com/od/typesofwood/p/WoodSizing.htm