Yugma provides desktop sharing, chat and white-boarding. It also supports VOIP conferencing, including a feature that integrates seminars with Skype calls. Presenters can use PC, Macs or Linux. Participants can use almost any system or browser by downloading a Java applet. A free, limited-functionality version allows up to 10 people to participate; more feature-rich versions start at about $200 per year for up to 20 people
DimDim is a fairly new, streamlined online seminar application with support for chat, slide sharing, emoticons, white-boarding, VOIP voice conferencing and video conferencing. Only PC desktops can be shared, but DimDim supports Mac and Linux users for other features. Participants can enter meeting rooms using almost any system or browser, typically without a download. A free, ad-supported version allows up to 20 people to participate; a version without ads starts at $99 per year for up to 20 people.