We use external libraries that have been written by someone, get bug reports and feature requests from the users, and rely on infrastructure provided by third parties.
So this is to say thanks for all of this. Thanks to the users, developers, testers, ... out there!
The number one scripting language around the world, the PHP core team did a very good job the last years, so we decided to use PHP for moregroupware instead of using Java, which was our second choice.
An incredibly powerful templating engine for PHP, written in PHP. It supports all the features you might ever need, and still is easily extensible. And, did I mention it is fast as well? No? It is, really...
A graphing library with a lot of features. We use it to generate the GANTT charts available in some parts of moregroupware.
This library allows you to generate PDF files without the need for PDF support being compiled into PHP. Great tool, and easy to use, too. Used for PDF generation in some parts of moregroupware.
An excellent database abstraction layer. We use it in favour of PEAR::DB, and are very happy with it. And just in case you wonder: Yes, we plan to make moregroupware really portable across databases as soon as possible!