Over the last couple of years I've become a convert to 3D Connexion's range of 3D mice. These more than double your productivity in any 3D application (such as Studio Cruz' stable of SketchUp, Rhinoceros, SolidWorks, and 3D Studio Max) by allowing both hands to be used - the left to manipulate the model/viewpoint and the right to create and edit detail. Though the top end model shown above is $400, the basic Space Navigator model can be found online for under $60 and has all the essential ability to spin, pan, and zoom of its big brother.
