Flint is an open-source project to create a versatile particle system in Actionscript 3. The result is a library that handles the common functionality for all particle systems, has methods for common particle behaviours, and lets developers extend it easily with their own custom behaviours without needing to touch the core code.
You can find more about Flint and join in discussions on our forum at the Flint website - http://flintparticles.org/