Making the best use of idle hands

Ok, so if you're a graphic designer or a 3D modeller, you probably spend a lot of time controlling a mouse with one hand while the other one sits idle, just sorta hanging out and wasting its time (at least that's how we imagine it).
Well, 3D connexion wants to put your other hand to good use, and is trying to convince people to start using a second device which is sort of like a small joystick to complement their mouse:

A SpaceMouse or similar device enables a designer to be much more productive and to reduce wrist strain by
minimizing the number of menus they have to click through in order to work on a project, Swarup said. "If we can get
you to use the other hand, which is sitting idle most of the time, you can be a lot more efficient," he said.

It's mainly for use with Photoshop or 3D modeling applications like Maya, but apparently it'll also work Microsoft Office.