Dimdim is a CentOS Linux-based streaming media and conferencing server that supports Internet Explorer, Safari, and Firefox browsers on Windows, Mac, and Linux clients. Users can share PowerPoint and PDF documents, whiteboards, and entire desktops, with audio and video conferencing and public or private chats. Like an open source WebEx, GoToMeeting, or Live Meeting, it is downloadable in a handy VMware appliance.