SubEthaEdit (Real Time Collaborative Text Editing)

Ace (Real Time Collaborative Text Editing)

EtherPad (Online Real Time Collaborative Text Editing)

iChat AV (Video Chat)

Skype (Video Chat)

Adium (Instant Messaging)

OpenWengo

GIT (Distributed Version Control)

VLC (Steaming Media)

Google Apps (Collaborative Tool Suite)

Opensource CMS Demos

Dokuwiki