I have always been RSI-free, despite some quite scary habits of sitting curled up with keyboard on knee, until starting a new job about 9 months ago. After some messing about, time off sick and a modification to my desk I'm back at work but still not quite right. A Kensington Expert trackball has really helped and I'm working on training myself to use it with alternate hands.

Rands, I do think you're right about the fidgeting, I work in a cramped office facing a wall with a co-worker so close beside me he's probably reading this now. There just isn't space to keep moving around although maybe I'll just go ahead and annoy everyone regardless!