Adblock Plus is one of the most popular Firefox Add-ons in the world, with over 10 Million daily users and over 100k downloads a day. They use phpBB to offer support to their users.
OpenOffice.org offers a free and fully-featured office suite which meets the needs of the common consumer all the way up to large enterprises.
It is the Italian Community for Ubuntu, a popular open source community operating system based upon the the Debian Linux Distribution.
Password Manager, Auto Form Filler, Random Password Generator & Secure Digital Wallet App.
Pixelmator is a popular commercial image editing software for Mac OS X users.
KDE is mainly known for producing the KDE Desktop Environment (used in Kubuntu) for Linux.