Joomla!
Joomla! is a feature-rich open source Content Management System (CMS). It can be used to empower anything from personal web pages to composite business portals. Joomla! is dependable, simple to install and easy to manage.

Geeklog
Geeklog is an open-source content management tool, which offers a broad range of modules.

Moodle
Moodle is a course management system created to aid educators developing online courses. It is offered in 34 languages, and includes a WYSIWYG HTML Editor. The user has a complete control of all course settings and can choose from a wide range of course activities including Forums, Journals, Quizzes, Resources, Choices, Surveys, Assignments, Chats, Workshops, user logging and tracking, mail integration and other features.

Nucleus
Nucleus is a set of content management scripts that allow users to maintain one or more weblogs or online journals and includes features like Authors, Drafts and Future Posts.

Open Realty
Open-Realty is a real estate listing and content management system, which offers attachments, a flexible search tool, a template system, and a Yahoo Maps interface.

WebSiteBaker
WebSiteBaker is a content management system based on PHP for simple website development. Its list of features includes a template-based front-end, multi-level modulated page support, multi-user administration, etc.

phpWebSite
phpWebSite is a feature-rich content management system, which offers announcements, menu management, document management, link management, photo albums, block makers, FAQ, a web pages maker, polls, an information categorizer, a calendar, a form generator, etc.


CUSTOMER SUPPORT
Crafty Syntax Live Help
Crafty Syntax Live Help is a live help chat system, which provides monitoring of visitors, multiple chat sessions, referrer tracking, page-view tracking, multiple operators, canned responses/images/URLs.
Help Center Live
Help Center Live is a feature-rich all-in-one help center, which offers live help, support tickets and FAQ. It features unlimited operators/departments, visitor monitoring, chat initiation, collecting of visitor information, tracking of visitor footprints, auto-saving of chat transcripts, canned messages, unlimited FAQ questions, etc.

OS Ticket
OS Ticket is an open-source support ticket system, which provides pop3 login, unlimited e-mail addresses, admin/staff/user panels, email intervals to prevent auto-responder loops, limitation of the maximum number of tickets a user can have opened, the ability to accept attachments, page alerts for administrators and more.

PHPTickets
PHP Tickets is a basic, single-administrator support ticket system, which includes self-registration, e-mails to the administrator, attachments, etc.

Support Logic Helpdesk
Support Logic Helpdesk is a support ticket system, which offers multiple e-mail addresses, admin/staff/user panels, canned responses, HTML tags support, e-mail limit on a per user/day basis, attachments and more.

DISCUSSION BOARDS
YaBB SE
YaBB SE is a PHP/MySQL port of the popular forum software YaBB (Yet another Bulletin Board), which provides the same user-friendly interface and several of the most popular modifications from YaBB's BoardMod program.
phpBB2
phpBB2 is a popular open-source forum tool with an easy-to-use user interface and an easily customizable administration panel.

EasyForum
EasyForum is an easy-to-install, XHTML1.0/CSS2 compliant and best viewed with any browser BBS written in PHP. No MySQL database required. The latest version is fully PHP3/4/5 compatible and translated in 26 languages.

E-COMMERCE
OS Commerce
OS Commerce is a feature-rich shopping cart with a large selection of modules and support for almost all payment gateways.
OS CommRes
OS CommRes ranks first among the most powerful open-source booking systems. The commercial solution is based on the secure, scaleable and reliable OS CommRes project. The solution includes a full Call Centre module, and key metrics such as inventory management, sales auditing, and bookings analysis.


FILE MANIPULATION
Invision Power FM
Invision Power FM is a popular file management script, which allows users to control their files through any modern browser.

GUESTBOOKS
MJguest
MJGUEST is a free professional guestbook, designed as hi-end solution for both personal homepages and corporate websites.

GROUPWARE TOOLS
DOTproject
DOTproject is a project management system, which includes companies, projects, tasks, forums, files, calendar, contacts, tickets/helpdesk, language support, user/module permissions, themes, etc.
PHProject
PHProject is a PHP-based project management system, which provides an optional group system, different stages of privileges, Calendar, contacts, Time card, Projects, Chat, Forum, Request tracker, Mail client, Files, Notes, Bookmarks, to-do lists, reminders, voting, language support and other features.


IMAGE GALLERIES
4Images Gallery
4Images Gallery is an image gallery script, which offers unlimited categories/subcategories, FTP upload of images, auto-generated thumbnails, comments, the ability to send and rate pictures, random picture display and a powerful administration panel.
Coppermine
Coppermine Photo Gallery is an image gallery tool, which provides categories and albums, thumbnails and intermediate size pictures, new and random picture displays, a search feature, user management (private galleries, groups) and comments, an e-cards feature, slideshow viewer and more.


PORTAL SYSTEMS
PHP Nuke
PHP-Nuke is a very popular community-based portal with a large choice of modules and languages. It features multiple capabilities such as web administration, polls/surveys with comments, statistics, user customizable boxes, a banner system, backend/headlines generation, a search engine, file manager, download manager, FAQ manager, etc.


SERVER MANAGEMENT
phplinks
phplinks is an open source PHP link management script, which allows users to run a very efficient Link Farm with complete search capabilities.

WEB HOSTING TOOLS
phpFormGenerator
phpFormGenerator is a form generator, which offers up to 100 form fields, various field types including file upload, customizable field attributes, the ability to send submitted data to an e-mail address or store it in a database, administration panel and other features.
phpcoin
phpcoin is a comprehensive billing/invoicing application, perfect for web hosting resellers to manage their customer orders, invoices, notes and helpdesk. The tool can be used by different types of businesses as well.