With so many concerns about the ergonomics of the mouse, why not just remove it altogether? After all, laptops and their touchpads have done just fine without them. Sweden's Mousetrapper Nordic apparently shares this philosophy, which is why it designed the "Mousetrapper Advance."
It's described on TechShout as a "unique electronic pointing device" and a "multi-dimensional steering pad," but to us it looks like a laptop-style touchpad built into a wrist rest. Marketing-speak aside, it could still be a good idea for RSI sufferers. For our part, we're sticking with the "MugMouse."