PowerSDK PRIM is a framework which provides runtime primitive types in Flash Player.

PRIM is a general framework for creating primitive types within the player and is extensible. Even better is the included event model, allowing you to receive events when a primitive value is modified without watching or polling the value for changes.

Ted Patrick made this. He is the one who keeps doing innovative work and kick ass project. These days, he is busy in FLOW and some python based server I guess.
He has made PRIM free and open . More details can be found here.
I have been part of PRIM Beta. I could not contribute much except reading comments and posting my ideas.
But it was nice project, a different kind of project.