Using the same principle as this unicycle here is another one that has a neat look. For more pictures have a look at the photo gallery.
Video 1
Video 2
Video 3

“The delicate balance gives the movements of unicycles a stiff and jerky quality. Automatic stabilisation, however, requires the unicycle to be fitted with a highly dynamic four-quadrant drive. The short reaction times required, in the range of milliseconds, entirely rule out combustion engines. Such high demands for stability and dynamic performance can only by satisfied with electrical drives. ”

Via: Hackaday