slooooooow… might be hackish but not very fun.

@kristian:
no, it’s basically the same, but what XenonJohn added on his one, it’s another wheel and another motor, so he can steer more easily, with a nunchuck for example.
he also built a mono-wheel version like the Ben Smithers’ one in charlie comment.
here’s xenonjohn website: http://sites.google.com/site/onewheeledselfbalancing/

if the project page is gone put it The Wayback Machine archive and find an old copy of it http://web.archive.org

Good links, I think i might have a go at one.

I’ve wanted to build something like this for a while now. It may just be the tech-nerd in me, but I think it would be fun to show up on campus riding one of these things! ‘course, I’m an engineer – so it wouldn’t be too surprising…

these all fall short when you try them on uneven ground (slope). maybe distance sensors on the front and back to keep the unit level with the ground might yield more utilitarian results.

instructables Booooo!

Also this identical design has been published many times before, even on this site.

Thanks everyone for the comments both constructive, and abusive.

A link to the code is now on the first page of my instructable, with a warning. Many do not openly publish code for self balancing vehicles because someone in this killjoy society may sue them if they fall off. They are not being pretentious pricks.
My website openly acknowledges every single segway and seg-skateboard builder I have found on the web. There are very few skateboard designs that actually work well. I am seeing how far I can go and documenting it.
The video you have included is the first showing this particular version of my current machine being ridden, and that includes on my own website. It went on Youtube one week ago.
I did not submit this to Hackaday either, they found me.
However if sending me a message so I can email you my (free) code, based on a couple of years of work, is too much trouble for you Mr xorpunk then you are really pretty unlikely to have the attention span to build anything like this.
If you can do better, be my guest – do something constructive.
You have put up the wrong video. The correct one is here:

I had so much interest, much of it from teenagers interested in electronics, when I showed my (expensive and tricky to build) machine (the video you have shown), that I have redesigned it to be as affordable as possible, as simple as possible to construct, and now runs with an Arduino micro, i.e. easiest to program. I have done this specifically to encourage people to have a go, widen the interest and expand this community of enthusiasts – I would call that constructive not pretentious. I am male though so I do indeed have a prick.
There are many other self balancing designs out there. Most are Segway style. Very few if any run Arduino code. Some balancing small robots do. The only reasonably workable twin wheel steerable skateboard I have seen with small wheels under the deck was/is the Emanual 1, which I have acknowledged clearly in my instructable. This used infra-red distance sensors each end. However if you know of any such designs with a hidden flat Lithium battery pack in the deck, wheels under the deck not sticking out of the sides, steered (not moved along) by a wireless Wii Nunchuck, light enough to be carried in one hand, that will go over rough surfaces, that have a >20mile range, then please do let me know so I can improve mine.
If you want to just go fast, you need a standard electic skateboard. They go up to 35mph and there are several makes.
If you want a normal skateboard, fine, none of this will be of interest to you.
John