If you stayed at home and never left your house, could you find enough programming work to survive? If not, you're probably not ready to try it while out on the road with less reliable access to communications. I have an American friend who is a software engineer and has managed to live in various places around the world while still working for U.S. companies. It works for him because:

1) He is very, very good at working remotely
2) He is one of the top guys in his field
3) He has a very large network of people and companies from which he can get work

All of these points are important, but the last one is the most important: if you don't already have a large network of people who know your work and are willing to hire you to work remotely you then you may find it difficult to succeed.

You could try finding work using sites that cater to remote "freelance" work (ex: elance.com, ODesk, freelancer.com, etc), just be aware that in many cases you'll be competing with workers in lower-wage countries so you won't be able to make a whole lot of money. Here's one example from eLance: the job was posted less than an hour ago and there are already 10 proposals from people willing to deploy an entire team of people (project manager, visual designers, programmers) to develop a complete mobile app for US$1000-5000. And that's one of the more lucrative jobs I saw! If your expenses while on tour are low enough, then maybe you could get by making only US$10-20 per hour. That's assuming, of course, that you have a portfolio of work convincing enough to land jobs on one of these very competitive sites.

If you need to make more money your best bet may be to find a contract programming agency or job recruiter in your home country, build up a reputation by completing several assignments with them while you're still at home, then see if they'd be willing to send you work while you're traveling.

You might also consider whether programming is the best way to make money while you're traveling. If you can write well or speak multiple languages, you may find that writing or translation work is easier to manage while you're on the road. Those sorts of jobs likely pay less than programming but you may find the assignments easier to complete or less time-consuming. Perhaps there is also a niche market for software translation or internationalization that would pay slightly better than standard written translation work? Not sure how you would find work, but I can imagine that a multi-lingual programmer might be valuable to U.S. software companies who want to expand their sales opportunities by translating their apps into French, German, Italian, Spanish, etc.