Free Flash Framework For Real-Time, Multi-User Applications : Hemlock
Hemlock is an open-source Flash framework which offers the richness of Flash & the scalability of XMPP.
It eases the creation of real-time & multi-user applications like games, collaboration and more.
Generally, real-time applications are handled with polling where a database is queried every x seconds to get the latest updates.
With the Hemlock approach, a client registers for a message and is only contacted when a relevant one arrives. This is clearly a better method as it is much real-time & cost-effective (no unnecessary polls).