Blogs:
b2evolution
Nucleus
pMachine Free
WordPress

Content Management:
Drupal
Geeklog
Joomla
Mambo Open Source
PHP-Nuke
phpWCMS
Post-Nuke
SiteFrame
TYPO3
Xoops

Customer Relationship:
Crafty Syntax Live Help
Help Center Live
osTicket
PerlDesk
PHP Support Tickets
Support Logic Helpdesk
Support Services Manager

E-Commerce:
CubeCart
OS Commerce
Zen Cart

Guestbooks:
viPER Guestbook

Extras:
Language
Side menu appearance
Email Notifications
Installations overview

Mailing Lists:
PHPlist

F.A.Q.:
FAQMasterFlex

Image Galleries:
4Images Gallery
Coppermine Photo Gallery
Gallery

Polls and Surveys:
Advanced Poll
phpESP
PHPSurveyor

Project Management:
dotProject
PHPProjekt

Site Builders:
Pro Edition
Templates Express

Discussion Boards:
phpBB2
SMF

Hosting Billing:
AccountLab Plus
phpCOIN

Wiki:
TikiWiki
PhpWiki

Other Scripts:
Dew-NewPHPLinks
Moodle
Noahs Classifieds
Open-Realty
phpAdsNew
PHPauction
phpFormGenerator
WebCalendar