One of E-Learning Queen's most popular posts in the past detailed open source webinar solutions. You may still visit that post. Times change quickly, though, and many of the solutions listed there are no longer viable.
So, as a service to readers, E-Learning Queen is publishing an updated list. Please feel free to share your experiences with the solutions. We'd love to hear your thoughts.
Moodle Solutions
Moodle Plugin from Sclipo
Download from SourceForge
Step-by-step Install Guide Moodle on Linux with Sclipo Live Web Class on Linux v1.4
Free PHP Code: http://phpkode.com/source/p/moodle-live-classes-and-webinar-plugin/sclipowebclass/index.php
Video Tutorials: How to install Sclipo
Bundled Open Source Solutions
BigBlueButton
Uses all open-source components (http://bigbluebutton.org/components)
Colloquium
Colloquium is a pedagogical tool for presenting online webcasts with supplementary materials. Streaming video is combined with a rich set of support materials - live chat, threaded discussion, and links.
Webcasting Plus
DCAST
EasyCast
Easy in use system of scripts to organize webcast from conferences and other such events. Allows maintaining video stream and presentation viewing together with asking questions from internet.
Desktop Sharing
Apreta
Apreta is about sharing information in real-time meetings. It provides desktop sharing, presentation sharing, a shared whiteboard, and audio conferencing.
Desktop Share - Class Room Integration (CRI)
This is a web application that enables integration between the teacher and student in a virtual classroom. The application gives users the ability to share a desktop with Teacher/Coordinator/Admin and Student can share his her desktop with Teacher/Coordinator/Admin.
Wedatoo
Wedatoo is an open source point to point realtime collaboration application like google talk which features text chat, file transfers, audio/video conferencing, whiteboard, image sharing and desktop sharing/control modeled on google talk.
DimDim
DimDim has an opensource webinar solution which is, at this point, free. DimDim has been acquired by Salesforce.com. We will see what happens.
Webmeeting
Web Conferencing system allow you to conduct the web conference around the globe. The system allow to share the desktop , application, dashboard, voice chatting and video conferencing.
ILIAS LMS
A full-featured opensource learning management system. Not apparent whether or not it has a plugin that allows webinars / webcasting with chat / whiteboard.
Webcasting
UStream
Streaming and webcasting do not have the interactivity of a packaged solution of WebEx, Omnovia, or GoToMeeting. However, you can piggyback services, and use UStream in conjunction with messaging / doc sharing
DVLabs
Stripped-down basic functionality?
Sofia-SIP
Session Initiation Protocol software