Forum OpenACS Q&A: Re: Pointers & Tips for Newbs?
General OpenACS articles
Excellent books on TCL, SQL, general web app development, ...
The problem sets might help
If you are comfortable with all of the above already, and the package documentation isn't helping you, try your api-doc installation or https://openacs.org/api-doc/ as many procs are well documented at the source level.
Some WimpyPoint presentations are useful:
These forums are of course one of the best sources for information. If you have AOLserver questions, there is also an AOLserver mailing list, WIKI, weekly chat on AIM, etc. OpenACS'ers are often available on IRC.