I had the pleasure of 8 days touring Sth Korea with my daughter whom is at Uni in Seoul, in February. By choice we stayed in 'Hanoks'; traditional Korean homes, and I delighted in the ondol heating in each. With a move from sub-tropical to cool temperate shortly, I'm converted as to the livability of these systems. It's not unheard of Down Under, (hydronic underfloor heating) but it's rare enough that I've only walked on it a couple of times before. My daughter, 10 flights up in a share apartment in Seoul, says that they can tell when all the apartments around them turn theirs on, as they get heated up too! Sometimes to the point of having to open the windows to cool off!
I got a few photos of my trip over, I was fascinated by the wooden pieces on the floor - all totally removable. (I didn't try!) I was a little tickled by the stylishly printed bubble wrap on the rice paper doors, too!
I'm flumoxed as to how to add pics though - I don't have a website that I put them on, barring my facebook account.
We did get to spend a (very wet) day at one of the Folk Villages on Jeju Island. That was amazing. There I got pics of the original ondol systems.