[thumper]

cough Worlds Chat cough

Seriously, we had that exact idea implemented around 1997 -- and it even supported multiple authentications (anonymous worlds, versus worlds with user accounts) all transparently. And it could even do VRML, crowd control, dynamic downloads (so you could link to new worlds), and a built-in world builder.

It seemed that we had thought of everything... And then management took over.

[pshc]

You should have let marketing take over and built up unsustainable hype and corporate endorsement instead ;)