Soulseek (http://www.slsknet.org) is a communication and file-sharing system. It is quite similar to Napster: it lets you exchange files, search for files, chat with other users in public and in private, browse their files, and get recommendations for music. SoulSeek for Linux is a GUI client for the system written in Python/wxPython. It includes all the major functionality: chat, searches, and file transfers.
scponly is an alternative "shell" of sorts for system administrators who would like to provide access to remote users to both read and write local files without providing any remote execution priviledges. Functionally, it is a wrapper around the ssh suite of applications. It is typically used by creating a user whose shell is set to scponly. This user can neither login interactively nor execute commands remotely, but it can use scp and sftp to download and upload files to the computer, governed by the usual Unix file permissions.
TorrentFlux is a feature rich Torrent client. Users can manage Torrent downloads through a Web interface from anywhere. Torrents can be uploaded via a URL or file upload, and can be started, stopped, and deleted with a click. You are also able to view the download progress of all Torrents, server drive space, and Torrent file meta information before and during download. It has built-in user management and security as well as private messaging between users. Each user is able to select their own theme and view the upload history. For administrators there is a detailed user administration and searchable logs. Various languages are supported.
This program hopes to become a viable MS Sharepoint clone. It is basically a Web interface to a document repository (Frontpage Web), but with many other features. It depends on Frontpage extensions for remote authoring; otherwise it is independent. It includes a forum, calendar, event tracking, announcements, tasks, file check in/check out, user management, email, and more.
eContent is a Web-based content management system for creating information systems, intranets, B2B, B2C, catalogs, and vertical portals. Written in Java for scalability, and based on open standards Struts and Expresso for stability, eContent integrates content management, scalable content and application delivery, resource management, workflow and personalization. It supports executables, all documents types, OLAP reports, Java programs, and legacy integration.
OPT (Outreach Project Tool) is a PHP general-purpose virtual commonplace for customers and developers to collaborate in developing projects. The system provides documents archive, e-mail archive, request tracker, task management, knowledge base, news administration, newsletter support, and a lot of other features (some project-based, some system-based).