It is the Italian Community for Ubuntu, a popular open source community operating system based upon the the Debian Linux Distribution.
The VideoLAN project produces the extremely popular VLC media player software. Their forums provide support for users of the software as well as the development community.
Fujitsu is a hardware and IT services company focused on providing IT-driven business solutions. Their community forum is powered by phpBB.
Active community for UK based Audi TT owners. Almost 30k members and 2 million posts, complete with unique style & powered by phpBB.
The Raspberry Pi is a cheap, credit-card sized computer. The official website uses phpBB for their discussion forums.
KDE is mainly known for producing the KDE Desktop Environment (used in Kubuntu) for Linux.