I've been to Japan twice, just holidays. The expats I've talked to have all agreed JET or JETS (not sure which) is the best. NOVA (I've heard that NO VAcation bit as well) isn't so highly regarded. I have a Japanese friend enrolled at NOVA, they apparently make you put down a non-refundable tuition for a long course, that a lot of times the students don't like. Not to knock those of you who teach at NOVA, but I've seldom heard a kind word about it. They are everywhere though, if location is what your after. Just look for the pink NOVA usagi.
I met a guy who tought at a uni who said it was probably the plushest job you can get, but they aren't easy to come by.
There are also jobs in modeling/acting, and if you're black, hip-hop stores. Most of them seemed to be from the Carribbean islands, if I had to guess.
One of my mates who went with me kept having bad luck with old Japanese ladies, he got attacked by a Shinto nun (nun is the closest approximation that comes to mind), the first trip. But overall, the Japanese seem really patient and helpful with "temporary gaijin" like myself. Keeping an open mind and respecting their culture goes a long way as well. They always seemed tickled when I was able to speak Japanese. But I don't really know much about living there long-term.
Caucasian males might find their popularity with the opposite sex goes through the roof in Japan. I'd try not to let it go to your head, and I imagine it wears thin after a while. I was at a Japanese high school for 3 days at the age of 18, which was well, quite an experience.