Houseparty - Brining empathy to online communication.
HEY - Email at its best, new from Basecamp.
Booyah - Video chat with up to 12 friends at the same time.
Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.
Airtime - Hang out with group video, share music & videos
InstAddr - Disposable email address application.