Some open source components, modules and plugins (not a lot at the moment as you can see) we've developed for Joomla! cms. All are free to download and released under the GNU/GPL license.
QTube
A simple plugin to embed YouTube hosted videos in any content item. A module is also avaiable if you need to include a video in any module position. Natively developed for Joomla 1.5.
QContacts
A contact manager component derived from the standard Joomla! component (com_contact) and offering several additional features such as the possibility to add custom fields and an anti-spam verification code (captcha) to the contact form. Natively developed for Joomla! 1.5.
QTabs (Beta)
Put multiple modules in a single module position and allow users to switch through them with navigational tabs. many styles and animation effects supported.
QCategories
Publish links to all categories of a given section in a module position. You can choose whether the page linked from each category link will be displayed with a table or blog layout.