Toon # 
1   Link   Joomla!
Home of Joomla!
2   Link   OpenSourceMatters
Home of OSM
3   Link   php.net
The language that Joomla! is developed in
4   Link   Joomla! - Forums
Joomla! Forums
5   Link   MySQL
The database that Joomla! uses
6   Link   Ohloh Tracking of Joomla!
Objective reports from Ohloh about Joomla's development activity. Joomla! has some star developers with serious kudos.