Sci-fi author Charles Stross is writing a series of blog entries on Common Misconceptions About Publishing. Interesting reads, particularly number 4, which goes into detail about translation and overseas publishing rights and so on and gives some helpful numbers covering the English-language markets (at least for SF writing).
The eighth and most recent entry, not linked on that index page at the moment, is called “Lifestyle or Job?” It gives some figures on author incomes that should scare you away if you’re thinking about getting rich as a writer. J-E translator incomes might be getting pinched by bargain-seeking clients and budget-slashing DPJ governments (more on that in an upcoming post), but I think we’ve still got it better than the folks who have to come up with their own ideas to put into words on the page.