DimDim is described as 'The worlds easiest web conference, lets you synchronize live presentations, white boards and web pages while sharing voice, video over the internet' and is an app in the Office & Productivity category. There are more than 10 alternatives to DimDim for a variety of platforms, including Windows, Mac, Online / Web-based, Linux and Android. The best alternative is BigBlueButton, which is both free and Open Source. Other great apps like DimDim are Cisco Webex Meetings (Freemium), OpenMeetings (Free, Open Source), GoToMeeting (Paid) and Twiddla (Freemium).
VoiceThread is a cloud-based media tool that allows users to collaborate on and communicate around media presentations that include images, video, and documents. The collaboration, interaction and discussion is asynchronous. No scheduling required.