Bad places for project documentation:

* blog posts
* mailing list archives, public
* mailing list archives, private
* private emails
* chat logs
* commit messages
* closed tickets
* open tickets
* letters to the editor, published
* letters to the editor, unpublished
* people's heads
* cave paintings
* DNA of custom bacteria
* interstellar probes
* value of pi

in reply to Lars Wirzenius