EGroupware is a Web-based groupware suite. It contains many modules, including Calendar (personal calendar and group scheduling, notifications and alarms), Mail (IMAP only), InfoLog (todos, notes, and phone calls linked to contacts/CRM), Contacts (an address book for storing and sharing contact information), ProjectManager, Tracker (bug or incident tracking), TimeSheet, SyncML, CalDAV & CardDAV support, and SiteMgr content management
BytesFall Explorer (bfExplorer for short) is a Web-based file manager. It allows you to upload, download, view, edit, copy, move/rename, and change permissions of a single file/directory or a group of files/directories. It's also possible to create files and directories and execute shell commands. An SQL engine is used to store the users for the authentication (currently MySQL and PostgreSQL are supported). It has an interface similar to Windows Explorer.
phpXplorer is an file management system and explorer that makes it possible to work on a remote file system through a Web browser. By default, it includes dialogs for editing HTML, PHP, images, Apache, compressed files, and emails. Its modular design makes it easy to build your own filetypes, property sheets, views, and themes. A permission manager allows you to restrict access to the shared file system for multiple users in a detailed way.
Kaolak is a Web-based community system. A Kaolak community is defined by its users and documents and forms a Kaolak branch. Kaolak is designed to handle many branches transparently from each other, within a single instance (one URL, one database). It features a permission scheme which allows users to give read/write access to documents they own to other groups/users. With a little PHP knowledge, modules can be implemented to extend Kaolak functionality.