Official Support Forum for Debian, the kernel-based open source operating system. phpBB provides a solid platform for support and discussion.
KDE is mainly known for producing the KDE Desktop Environment (used in Kubuntu) for Linux.
Solia Online is one of the most active online communities with over 18 million posts. Solia Online allows you to create your own avatar, buy items, and discuss topics with your friends.
OpenCart is popular, powerful, and easy to use shopping cart software. Their healthy community forums are powered by phpBB.
Support for Synology NAS devices and ideas for future versions of the DiskStation software.
Hugely popular Mozilla community providing support for Firefox, Thunderbird, Seamonkey and other well known Mozilla products. Over 350k members and 4 Million posts.