http://openacs.org/bboard - the OpenACS installation and configuration bulletin board.
http://openacs.org/sdm - all bug reports and feature requests should go here (including corrections/suggestions to this documentation).
If you want to help with the OpenACS project, email ben@mit.edu
http://yourservername.com/doc. Once you have your OpenACS system setup, the /doc directory contains documentation about all modules and many other aspects of the toolkit.
We get this question many times. Ben Adida wrote a short article explaining why OpenACS doesn't use MySQL (which made into Slashdot, giving openacs.org 37,000+ hits on that day). Read it at http://www.openacs.org/why-not-mysql.html.
You can read more about this on the article that explains why Sourceforge.net has moved away from MySQL, at http://www.phpbuilder.com/columns/tim20001112.php3.
aolserver.com and especially aolserver.com/doc for AOLserver info and documentation (also included in the source distribution).
ArsDigita Systems Journal for lots of good quality information on AOLserver, the ACS and building great web services.
OpenForce Inc, provides commercial support, customization and other services using OpenACS.