Fantastico De Luxe is an amazing cPanel/PHP based Web application. It integrates with cPanel and gives you and your clients the ability to automagically install below listed popular Open Source Applications. With Fantastico the installation procedure of all of the following scripts takes only seconds and can be performed by novices without the need of setting up MySQL databases, importing structure, chmoding files and without the need of other tasks usually associated with installations:

Discussion Boards:
phpBB2  - very popular "forums" or "message board" solution
SMF - another popular choice for a full featured "forums" or "bulletin board"

Portals/CMS:
PHP-Nuke - a powerful portal solution with many modules, blocks and addons available
Post-Nuke - another powerful CMS portal site also with many modules, blocks and addons available
phpWCMS - a CMS system
phpWebSite - a CMS portal site with many modules and addons available
Mambo - a dynamic web content management system (CMS), capable of  building sites from several pages to several thousand
Siteframe
Typo3 - a Web content management framework
Xoops - a CMS portal site with many modules and addons available
Drupal
Joomla! - a Content Management System (CMS)
Geeklog

eCommerce:
CubeCart - a popular shopping cart system
osCommerce - a powerful highly configurable eCommerce shopping cart solution
ZenCart - another user-friendly open source shopping cart system

Customer Support Systems:
PHP Support Tickets - powerful Support Ticketing System to help you help your visitors
Support-Logic Helpdesk
Support Services Manager - a powerful system for providing your visitors and clients with support services
osTicket
Crafty Syntax Live Help (CSLH)
Help Center Live

F.A.Q.:
FAQMasterFlex  - a database-driven application for creating and maintaining Frequently Asked Questions (FAQs)

Blogs:
b2evolution
Nucleus
WordPress

Image Galleries:
4images Gallery - your own online photo gallery
Gallery - probably the most popular image gallery script
Coppermine Photo Gallery - a feature-rich photo gallery script with MySQL database, user management, private galleries, automatic thumbnail creation, film strip, and a template system for customization

Polls and Surveys:
Advanced Poll - polling system with multiple polls, templates, IP-Logging, IP-Locking, cookie support, etc.
phpESP - a PHP/MySQL-driven application to let non-technical users create surveys
LimeSurvey - surveying tool that allows you to develop, publish, manage surveys

Mailing List:
PHPlist

Wiki:
PhpWiki  - a PHP clone of WikiWikiWeb, a web site system where anybody  can edit the pages right through the web browser, without any
    authentication
Tiki Wiki - Tiki features a Wiki, Image galleries, File galleries, Forums, Polls, Chat, RSS feeds, Articles, Submissions, Weblogs, Webmail, Surveys, Trackers, Newsletters and more. Themes can be created using CSS. Everything is customizable

Project Management:
PHProjekt - a project managing system for tasks and groups dotProject

Other Scripts:
Moodle - Moodle is a course management system designed to help educators create quality online courses
Noah's Classifieds - run your own Classified ads website!
Dew-NewPHPLinks  - Dew-Code is a resource for aspiring coders.
Open-Realty - professional but free tool for real estate agents to put their offers online
phpAdsNew
PHPauction - host your own auctions site!
phpFormGenerator
WebCalendar - a PHP application used to maintain a calendar for one or more persons

With Fantastico De Luxe you can
- install in the main directory, in addon domains and in subdomains
- create Features Sets so different users have different set of available scripts
- translate the English language file and give your clients auto-installation in their own language
- get notifications when users install/remove applications
- have a complete overview over the installations performed by your users