This is cross-posted from Geeky Traveler.
A few months ago I saw Steamboy. Like most anime films I see, it only made about 60% sense (Hayao Miyazaki’s films are more like 40%). Among the many bizarre steam-powered inventions in the film was the protagonist’s one-wheel cycle or ‘monowheel’:

When I followed Mirabilis’s reference to the Wheelsurf, I experienced a certain anime/real-world Matrixesque deja vu. Check it out: [more]

The site’s prose is a little purple (or a little is lost in translation?), but here’s the blurb:
The Wheelsurf is pure adrenaline. It is one of the most distinctive vehicles on the planet — a single-wheeled , ride-inside conveyance that’s sure to get you noticed. Riding the Wheelsurf is not for those seeking transport alone…
Imagine yourself in a centrifuge. The world is all yours. It is you and gravity forces. You are in the pipeline, the road is like water and you are surfing on it. It is fun, excitement, it is a thrill.
There’s no word on a steam-powered version, but we can always hope.
I think the trick to understanding Miyazaki films is a liberal dose of hallucinogenic mushrooms – “Spirited Away” made so much sense after that.
Miyazaki stories echo the world the way children see it, not adults. Try watching with a 3-year-old’s perspective – for a kid, life doesn’t often make a lot of sense. They have very little control over what happens to them – people come and go without explanation, rules are created and enforced arbitrarily, adults talk about incomprehensible things like jobs and mortgages and political reform – so kids just go with the flow and make the best of whatever situation they’re in. Miyazaki’s movies follow a similar pattern – there isn’t a coherent storyline, just a series of loosely connected events, and no definitive resolution.
I recall seeing such a one-wheeled cycle on “That’s Incredible!”, so something like that has been around at least since the early 80’s.
Ahhh, here’s a motorized version of the same concept. Alas, not steam-powered.
http://www.americanroadshop.com/The_Monocycle/the_monocycle.html
They even made one on an episode of TV’s JUNKYARD WARS. I don’t think it worked very well, though.