Building a 36er bike
There was an article in the CTC magazine recently about a guy who'd built one. Their website has a FAQ which might be of interest.

Details include:


Tyres/tubes from unicycles
Needed very large disk rotors to make it stop 203mm.
Claimed to fit people of 5ft 3in to 6ft 5in (yes, I was surprised).


Also, I've spotted an example here which looks a lot like the picture in the magazine.