PeerProject is a versatile peer-to-peer filesharing client and file manager. It's intuitive and aesthetic while supporting many networks and features, including BitTorrent, G2, Gnutella, eDonkey, DC++, IRC, HTTP/FTP, and more. It's a mainstream fork of Shareaza p2p, for Windows and WINE.
openPLM is a Web-based Product Lifecycle Management (PLM) application. It provides a configuration management system that manages all kind of files and data as documents in a product structure. It supports documents, parts, BOMs, part-document links, electronic signatures for objects, revision management, check in and check out for all files, plain text search using the Xapian engine, navigation between objects using Graphviz, and user management that allows sponsorship, delegation, and rights. Plug-ins are available for Thunderbird, OpenOffice/LibreOffice, FreeCAD, and Gedit.
The Taridium ipbx is a complete software-based VoIP PBX system that replaces a traditional proprietary hardware PBX. It runs on Linux without the need for extra software licenses, and is based on the SIP standard. It supports many phones and is available for free in a 5 user version.