A Spaceball is a six-degree of freedom joystick. (three axes of movement + three axes of rotation) It is primarily used for navigating (panning and rotating) in 3D space, within 3D modelling or CAD programs on graphical workstations.
The joystick is a ball situated above the work surface so that it can easily be gripped. It can both be nudged in any direction and twisted slightly around any axis, with spring-loaded centring.
The device has multiple buttons - the layout differing greatly between models.
The Spaceball was originally developed as a controller for USA's Space Shuttle's robotic arm.
Several commercial models were produced between 1988 and 2006, manufactured by Spacial Systems, Spacetec IMC Ltd. Labtec and later 3DConnexion (a division of Logitech). Several of these have been resold branded by Silicon Graphics, HP, IBM and others.
After astronauts had complained that the ball was uncomfortable, 3DConnexion changed the ball into a flatter "puck" and changed the name to SpacePilot. 
Several other similar devices have been made by different companies, such as the Logitech Magellan SpaceMouse, 3DConnexion CadMan, SpaceNavigator and SpaceExplorer.
Some joysticks for gaming can twist slightly. Some games support the use of such joysticks for panning and rotating maps in 2D in similar manners to how the SpaceBall is used for navigation in 3D.
- Spacemice.org - Fan site/Wiki about the Spaceball and similar devices.
- Cadalyst.com: First Look: Space Pilot-Intelligent 3D Motion Control. 2005-09-01. Retrieved 2016-06-03