DimDim is a free open-source web conferencing client. DimDim is currently in alpha, so beware of bugs, but it has a lot of promise. Currently only Internet Explorer is supported for the presenter, though reportedly other participants can join via Firefox, and other browsers. DimDim is planning to expand to Firefox and Linux in the near future, daily updates available on SourceForge.net. DimDim sounds as though it will do just about everything Webex does, except it will be free. Stay tuned for updates on this up-and-coming web app. Alpha tester signup are being accepted, but no word on how long to try it out live. You can view the interactive demo at the DimDim.com
Shared application on Presenter view.
Shared Powerpoint on Presenter view.