As mixi follows OpenSocial, they plan to release some of APIs to developers.

Currently their APIs are only available to some of advertisers on mixi.

Here’re some of known APIs and methods to retrieve data from mixi. And please note I never am a programmer, so I can’t answer any technical questions.

Getting Ashiato, list of users viewed your profile

You can see who viewed your profile by visiting:
http://mixi.jp/atom/tracks/r=2/member_id=myMixiID

after logging in. You’ll be able to view a list of visiters of your profile in ATOM. I just tried this now, and it worked. Please visit this Japanese blog for more information.

PHP sample available here.

mixi station API

Unofficial explanation on available APIs in Japanese.
http://teahut.sakura.ne.jp/b/2007-07-01-1.html

mixi station is an official desktop widget to show updates. Downloads only available to mixi.

Wow! There’s document in English!

I’m writing this as I search, so this things happens a lot…

Here’s the link to document site. It’s NOT official.
http://www.doyouphp.jp/pear/Services_MixiAPI

Here’s another PHP sample written by the same person.