Imagine a keyboard that could deliver not just the standard 88 notes, but the infinite array of tones between them. That's the idea behind University of Illinois researcher Lippold Haken's "Continuum Fingerboard."

Although the performer sits at the device much as he or she would at a keyboard, that term is a bit of a misnomer-there are no keys. Instead, fingers move along a smooth red cloth, under which lies a row of 256 rods mounted on springs. Pressure to the surface depresses the rods, the movement of which is monitored by tiny magnetic sensors. Sliding your fingers sideways along the board produces any pitch you want, as with a violin. Moving them front to back affects the brightness of tone, and varying the pressure alters loudness. Haken has built a half-dozen of the fingerboards and doesn't see mass popularity in the near future. "It's very difficult to play," he says.