WebEx - Cisco owned on demand web meeting tool is very simple to use.
Slidelive is a browser-based free WebEx competitor in beta. Presentations can be easily uploaded and conference calls scheduled to review them.
helps in creating and sharing presentaions.One can publish uploaded presentations inside their websites and blogs.
Zentation it is where one can combine presentations with Videos.
TeamSlide is a personal web application to actively present PowerPoint®-type slides to one or more viewers over the web.
DimDim (open source)
1VideoConference is an Open Source web conferencing facility which allows its Web, Audio/ Video phone, Skype, MSN and Yahoo users to instantly participate in live web conferences without the need for lengthy downloads or complicated installations. It is now known as VMukti.At any time, one can simply drop a small piece of code onto their websites and INSTANTLY create their very own online video conference room.