This tutorial project basically began on a free tripod website: http://jcc_7.tripod.com/d/tutor/.
Then, a PHP/MySQL system was developed at dsource (it was located at http://www.dsource.org/tutorials/). It ran on PHP/Postgre in its last days, but it's basically the same idea as it was with MySQL. I don't have any complaints with Postgre, but a few things broke in the conversion from the original MySQL database. The live version of the old system isn't available any longer, but a couple snapshots are available in the SVN: