Someone on the
japanese comm recommended this
http://lang-8.com/ website. It's a blogging/social networking site, where you write in the language you are studying, and correct blogs written in your native language. For example, if I write in Japanese, hopefully some Japanese person will correct my sentences, and in exchange, I correct their English sentences.
It looks like a fairly new site; not many users/posts/groups at the moment, but if it takes off it'd be pretty nice. Of course, I have so many blogging sites already, not sure if I can keep up with another one...
The majority seem to be Japanese-English exchanges (also, the layout looks suspiciously like Mixi.jp - I wonder if they'll get sued over it?), though there is some Chinese exchange (I would get into it if I knew how to type Chinese... maybe I will give it a go?), and Spanish and French and things as well.