Of course, reading Japanese is a bit more of a challenge than your average western language, for obvious reasons. I think that's one of the reasons I picked it, because I wanted to take on that challenge. Mastering it would be worth it for its own sake because of that, but beyond that, I'm rather taken by the beauty of Japanese (and, of course, Chinese) writing. There are other reasons as well, but those are the main ones.

In the process, I started to work on some rather complicated drill programs (I'd done generic flashcard programs before for my own use, but doing that for Japanese is orders of magnitudes more difficult). Mostly I did it because I didn't like the other drill programs I'd seen, but partly I did it because I could. I learned a lot just in the process of building them, and probably more in the process of building data sets for them (which is the real challenge -- the programs themselves were ultimately fairly easy). At any rate, I've put a copy of the documentation for them up online here.