PHPNuke and PostNuke make it easy to build Web portals and communities. They manage news articles, discussion groups, blogs and more.

Find out more:
http://phpnuke.org/
http://noc.postnuke.com/

Discussion Boards

PHPBB2 and Invision Power Board make it easy to add a powerful discussion group or forum to your Web site. You can have an unlimited number of forums and categories with full user management, search and moderator capabilities.

Find out more:
http://www.phpbb.com/
http://www.invisionboard.com/

Chat

PHPOpenChat lets you add a fully functional live chat system to your Web site. Use it for customer support or just to chat with others on the Web!

Find out more:
http://phpopenchat.org/

Photo Albums

With Gallery, you can easily manage and display your collections of images on your Web site. You can organize your pictures into albums, add captions, and create thumbnails. Gallery automatically keeps track of which pictures are most popular, and even lets viewers leave comments!

Find out more:
http://gallery.menalto.com

Web Form Management

FormMail lets you get the results of forms on your Web site through email. Just post your form to FormMail and it will take care of the rest!

Find out more:
http://www.dtheatre.com/scripts/formmail

E-commerce

OSCommerce makes it easy to build profitable Web-based storefronts. It helps you manage product catalogs, prices, customer accounts, orders and shipping. Your storefront can even offer bestseller lists, customer product reviews and product recommendations.

Find out more:
http://www.oscommerce.org