InstantPresenter alternatives

InstantPresenter
InstantPresenter is an online live presentation system that provides an effective way to upload and deliver live PowerPoint presentations on the Web. The new service also integrates an audio-video stream going from the presenter to all participants. InstantPresenter is fully cross-platform and can be used easily with both PCs and Macs. Text chat and an interactive group whiteboard are well integrated.
InstantPresenter alternatives are:
GoToWebinar