Yuuguu - Online Presentations, Remote Teams - Completely Cross Platform

Yuuguu is a screen sharing and instant messaging service
Download Yuuguu and show what's on your screen using screen sharing. Your viewers only need a web browser to watch, chat using instant messages and even make changes by allowing remote control of your computer - if you want them to. Speak to the group using our low cost voice conferencing - clearly to your viewers speakerphones.

Yuuguu for Online Meetings, Online Presentations, Remote Teams and Remote Support
I know there are tons of services like these but this the first I've seen that works Completely Cross Platform

Blogged with the Flock Browser