If you want to develop multi user applications, there are a number of technologies available out there, I’m not going to list them all, but recently, I worked with The Union Platform, Red5, and I also had a look at Stratus and AFCS.
AFCS is quite interesting because it provides loads of features “out of the box”, and if I had to develop a “professional” / commercial application, this is probably the solution I would choose.
Anyway, I made a simple “shared ball” application (just like the one that comes with the Red5 samples) and I wanted to share it with you …
Shared ball demo | Shared ball source code