There are similar things on the site below. Most are motorized but the first few aren't.
This one is pretty badassterous:
Their description: "In 1869 the craftsman Rousseau of Marseilles built this monocycle, which perches the cyclist on the inside of a 2 1/2 yards-high wheel. As there is no steering mechanism, it makes uncommon demands on the rider's sense of balance."
Thats right. Brakeless may be a big deal in our wimpy modern world, but no steering is a real test of a rider.
http://www.dself.dsl.pipex.com/MUSEU...l/motorwhl.htm