like somoene just above me said, stocks or forex.
you can trade on the market you want.......so you don't necessarily have to "work" the 9-4 hours the US stock market is open, but you could work "second" and trade on the london stock exchange, or even trade forex 24x7.
also my friend informed me of this which is kind of interesting. air traffic controllers must know english....this isn't a problem for you obviously, but I was kind of amused thinking that english is the air traffic controller universally accepted language. that could mean job prospects in all kinds of places where other people would struggle for a job.
if you can make a living off stocks you have to be either good and manage risk really well, or you need to have a couple million laying around. Because you could really easily invest in low risk stocks, and live on the dividends alone if you had 2-3 million.
The only downside to this profession is that well, not everyone has enough cash to be able to live on dividends.