invite only threads

Is there such thing as an "invite only" thread on this site? And if so how do you set one up?

nope, that would defeat the purpose of having a community discussion forum. If only people you want to discuss a topic, the topic will die a rather quick death.

and from a technical standpoint, it would be a bitch to set up. Forum permissions are confusing enough as it is, lets not throw something like that in the mix.