Build a two wheeled vehicle with active balancing, similar to the segway, but without it's steering column.
Build into the platform a force sensing device, similar to the Wii Fit.
Accellerate when the driver leans forwards, slow when he leans backwards, turn when he leans left/right.
The force sensors in the platform detect which way the driver is leaning, eliminating the need for additional steering hardware.-- goldbb, Mar 24 2009 I though the Segway column was for the person's balance stability and not for steering. Once a person is Segway capable the column isn't really needed, riding a bit like a surfer.-- wjt, Mar 24 2009 User Handbook: Please note the evolution of an inner ear is required for this product.-- eight_nine_tortoise, Mar 25 2009 random, halfbakery