I can speak a little about teaching English overseas. I'm American, and I spent 5 years teaching in Taiwan (w/ a BA in English) and 1 year teaching in China (w/ an MA in TESL).
If you have any specific question, let me know.
Personally, I wouldn't do JET. The folks I know that did were worked harder and paid less than people that found their own jobs. In Taiwan, the jobs that would give you a visa tended to pay less than the ones that didn't. So my goal was to get a visa for the least number of hours. I got my work visa from a place where I taught from 6:30-9:30 PM, M-F, and I worked elsewhere in the afternoon for more money. At the time (1999-2004) I got 550NT/hour (~$16) for the visa job and 800NT/hour (~$23) for the non-visa job. I worked about 25 hours a week, and both of these jobs required almost no prep and no grading, because (as the foreigner) was doing conversation / speaking. My non-visa job was at a cram school (bushiban) for elementary aged kids, my visa job was w/ adults. I had no teaching experience prior to moving to Taiwan.
I made ~$24K per year, which may not sound like much, but I saved ~$10K per year, despite spending lots of money on travel (Japan, Thailand, Guam, etc.), music gear and booze. My rent (2 bedroom apt w/ AC) was like $250 per month. I bought a scooter for $300 which I used for 5 years then sold. I ate out every lunch and dinner for $2-3. I certainly could have saved more (if I cut out the booze, for example) and I also could easily have worked more -- almost everyone I knew did private tutoring, etc. People were always offering me additional jobs, I just wasn't interested.
I really liked Taiwan. One cool thing is that you end up getting all sorts of weird opportunities. For example, I was the voice of a speaking dictionary (which paid very well), I launched a magazine w/ some friends, and I had a fairly successful band (way more successful than we would have been in the US, at least). It was great, and I love the fact that I spent my 20's living overseas, because it gets harder as you get older (now 38 w/ wife, house, kid).
China is OK, but the pollution there is really spectacular. Taiwan is somewhat polluted, too, but not like China. One really great thing about Taiwan is it's proximity to other places. I'd certainly recommend visiting China (I biked for a month in Qinghai, which was great) but personally I wouldn't want to live there again.
I'd recommend Taiwan or South Korea. Japan is great if you can find a good job with housing provided, but if you end up paying for housing it can be expensive. I don't really know anything about regions other than Asia.
As far as finding a job, I used Dave's ESL Cafe to find my first job. That said, I only did that job for a year (my boss was nuts). My recommendation (for Taiwan, at least) would be to go there on a 2 month tourist visa, find the city you like, then find a job. In my time, that was very easy to do. And it was also easy to switch a tourist visa to a work visa w/out leaving the country. I assume that hasn't changed, but I'm not sure.
Feel free to PM me (or post here) if you have other questions.