The SpaceExplorer uses 3D Connexion's unique six-axis technology to replace your PC's mouse with a push-pull-twist-tilt system of hands-on control.
The SpaceExplorer is ergonomically designed, with the controller surrounded by a wrist pad and a selection of easy-to-reach pre-programmed buttons.
Although the 3D Connexion website suggests the Windows-native SpaceExplorer is not Mac compatible, drivers are available to download for Mac OS X users.
The SpaceExplorer is most effective with 3D applications. You can use it to zoom, rotate, and fly through any of the popular 3D programs - including Second Life, where it offers a more fluid experience than mouse navigation does.
The catch is that there's no standard for 3D, so every application needs its own driver. The SpaceExplorer also works well for zooming around images in Photoshop or maps in Google Earth.
The problem is the price. The SpaceExplorer is far, far from cheap, and if you're wondering if it's worth the money, for most users the answer would have to be 'no'.