LearnCentral, a new social learning network for education, provides free virtual meeting rooms with two-way VoIP, multipoint video, interactive whiteboards and other useful applications. LearnCentral can be used to connect with up to two other people or locations.
The free version of Yugma's web conferencing software supports up to 20 attendees at once. You can share your desktop with all of the attendees and use the built-in instant messaging service to chat throughout the presentation.
Mikogo is a free service that can be used to conduct online presentations on the fly. You don't have to upload your presentation files in advance and you can share your desktop with up to 10 people.
Present.io is a no setup, web-based tool that allows presentation participants to see what you are doing on the Present.io site in real-time. Participants are also able to download, embed, share and comment on everything they see in the presentation.
ConnectNow is a free Adobe product that allows people to share screens and meet on the web. No download is required - all that is needed to participate in a ConnectNow presentation is the free Adobe Flash Player.
Empressr is a rich media presentation tool that can be used to create story-like slideshows with video, images and audio. Slideshows can be published on the Empressr site or embedded on a blog or Web page.
IMPRESS is a free multimedia presentation tool for OpenOffice.org. It is similar to Microsoft's PowerPoint but with additional capabilities such as 3D image display.
authorSTREAM is a free service that makes it easy to share PowerPoint presentations live online. Presentations can also be turned into a video for simple sharing via YouTube, TeacherTube and other video-based sites.
Free for instructors at any U.S. or Canadian university or college, LectureTools is a simple system for sharing slides, learning objects and other resources with students. It can also be used to upload and share podcasts.
Google Buzz isn't designed for online presentations, but it could be used for this purpose. Text, photos and videos can be shared privately, and people who are viewing your presentation can add their own comments to everything you publish.