Just want to hint that we (my company, that is) have made Typo3abc free to grasp & modify.
In a previous post of 2006, I wrote about the need to make the client understand the logic of what the information system you are building is about. This time I give some suggestions on how it's done.
One of the strengths of TYPO3 is its extension framework and we all have our favorite extensions. But have you thought about voting for their developers?