Pretty simple. A private forum costs 200 or 250 fg each with a limit of 3 or 4 or whatever.

You are a mod for that forum (sticky/close topics or whatever). You invite others into the forum and can give them mod privileges if you want. You can name the forum whatever you want. This has worked great on www.goallineblitz.com and I would love this ability here!

This feature is already available for guilds as Guild Notebox Pages.