Not everyone you see as a "guest" is not a member. Some are long-time members who have chosen to be "invisible," so no one but moderators can tell what they are going, or that they are online.

However, we have always had plenty of "Lurkers" or "guests" - anyone who wants to register is free to do so - literally, as it doesn't cost anything. Just hit the "register" link - the upper left side of the page in the blue bar. Follow the steps, and viola! - you're a member!