It is 'extesnion' in TYPO3. And it is 'module' in Magento. All another systems call them 'plugins'
13.08.2011 ws_facebook
Facebook: The last Activity
14.06.2011 ws_map
Graphical map of offices
05.05.2010 ws_404
404 Handler
16.04.2010 ws_wordpressgrab
Wordpress grabber
05.03.2010 ws_contentpagebrowser
Content with PageBrowser