The Blob

Here is a very interesting work on 3D in Flash from Russia, this engine is very powerful and can provide fluid online experiences.

http://blog.alternativaplatform.com/en/

It seems that their main goal is to propose multi-user application, which will allow people to create their own personal 3D world :

"Every company or end-user will be able to create personal 3D-world and to fine tune it according to own goals and preferences. We aim to give talents an opportunity to develop, to give developers tools to create great projects, to let business to market their goods and services through their own innovative personalized multy-user media."

Found via Mr DOOB