Blogroll for tag groupware
Zimbra - An innovative open source messaging and collaboration application
more.groupware - The free web based groupware solution written in PHP
phpGroupWare - A multi-user PHP groupware (calendar, todo-list, addressbook, email, news headlines)
eGroupWare - Another web groupware system
The Horde Project - A open source groupware that has webmail, contact manager, and calender
37signals - A company with an array of web applications for small business software, collaboration, project management, and CRM (basecamp, highrise, backpack, campfire)
