It's too early to tell if this approach really has legs but if I can keep it up it's hard to imagine what would entice me back into a salaried job again.
I think the only thing that would make me consider a full-time salaried job again is a family to support.
What's your cost of living like in Nha Trang?
Vietnam is very cheap. I can live quite comfortably here for about $1000/month and I could squeeze it down to about $600 if necessary. I'm currently renting a big, comfortable house within walking distance of the beach for about $350 a month. If you're at all interested in the hacker commune idea you could easily fit four people in a house this big and basically live for peanuts.
(I'm in a fairly similar situation, spent a few weeks in Vietnam this April, currently spending 3 months in Thailand, and then headed off to Japan - pretty much planning on bouncing around from country to country over the next few years.)
Japan would be fun too but you burn cash a lot faster there.
One of my major concerns is finding apartments. How do you manage to find short term leases, especially when you don't speak the language? I'm also curious about how you handle health insurance and cell phone usage. Could you point me in the right direction with these things? Any links would be great, my email is in my profile if you don't want to keep going on this thread.
For insurance I've used World Nomad's travel insurance.
You'll find that a lot of startups will be very flexible to your needs, the worst you can do is ask and see.