I'm working on a web project, where a user can share his screen and the output of his sound card with other users. I've come pretty far with the Adobe LCCS service (http://www.adobe.com/devnet/flashplatform/services/collaboration.html), but the screen sharing isn't stable enough to transmit a running video from the user's computer - it stops every 2 seconds.
It seems the only other way is to use a Java Applet. There are several libraries to share the screen. I'm looking for a way to capture the screen contents and stream it via RTMP to a server.
I have found a Java Applet, which captures screen shots of a defined area in a certain interval, encodes it into the ScreenVideo codec and streams it to an RTMP capable server: http://code.google.com/p/red5-screenshare/