TrackPoint

The pointing stick (trademarked by IBM as the TrackPoint) is an isometric joystick used as a pointing device (compare especially touchpad). It was invented by research scientist Ted Selker. It is present on many brands of laptop, including IBM's line of ThinkPad laptops (now made by Lenovo) and on Dell Latitudes under the name of Track Stick. It has also been observed on computer mice and on some desktop  keyboards, such as the UltraNav. Pointing stick devices are sometimes informally referred to as a "nipple" , "eraser head", "clit-mouse", or "nub" .
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<hardware> (Or "pointing stick", "nipple") A small knob found in the middle of some keyboards that works like a very short isometric joystick. Pressing it toward or away from you or from side to side moves the pointer on the screen. Ted Selker brought the concept of an in-keyboard pointing device to IBM in September 1987. TrackPoint was introduced in 1992 on the IBM ThinkPad and later on some desktops.
It takes up virtually no extra room on the box or the work area and also requires minimal movement of the hands from the keyboard.
Many imitations of highly variable quality appeared. Pointing sticks have also been used in many other notebook brands, including TI, HP, Compac, Dell, Toshiba (e.g. Portege 4000's "AccuPoint II"), and AST (e.g. Ascentia 910N).
"TrackPoint" and "Trackpoint" are IBM trademarks.
http://www.research.ibm.com/mathsci/cmc/trackpoint.htm.
[INTERACT'90, North Holland Pub Co, pp. 700-706].
(2003-10-15)