KA Contributions
Khan Academy's live-editor, which powers their computer programming environment, is open source. I've made a couple of contributions to this code-base, and so am thanked for help with Special Projects on KA's volunteer page (under the name MatthiasSaihttam).
KA's Volunteer credit page.
I've also reported a security bug, and have their "Friendly Hacker" badge.
I was able to review KA's AP Computer Science Principles content before it was publicly available.