We are a bunch of people that do virtual BDSM in addition to our ordinary BDSM activities. We use Second Life as our tool for communication and it works very well for discussion groups too.
There are of course other platforms and one of them is 3Dkink.com which runs under the umbrella of kink.com which in my opinion does some quality BDSM porn.
The 3D kink platform offers you a wide range of possibilities and tools to get your online kink going. It might not be as versatile as Second Life, but it seems to be a good alternative.