Obviously, you use mixi for practicing English, but what about elsewhere? I think it is safe to say nearly everyone on mixi is either Japanese, speaks a little Japanese, or at least has heard a Japanese person's accented English (both good and bad!).
Do you use sites normally used by native speakers, such as facebook or twitter?
Interesting comments. I guess with blogging being so popular in Japan, and Facebook and MySpace not being so popular, it makes sense that Mixi is popular because it is essentially a blogging engine. Twitter is micro-blogging, so that may explain why it is taking off so quickly in Japan. Do you agree with that?