We have 3603 accounts atm, actually. About 350 unique users visit us on an average day. About three dozen of us are probably responsible for 90% of the comments and posts. I guess that follows a 10:1% rule for lurkers, and engagement.
FB has some interesting accounting methods. For example, if you login to Digg, but never visit FB, you're counted as an active user.
This is one reason most advertising models are so awful. The motivation becomes numbers. On the other hand, if people pay for the service, the motivation is to improve the service. I don't want to get into a situation where I am focusing on the number of visits we are getting. I want to only worry about the quality of the time spent here. Not saying that I am planning on charging a fee, but I'm not going to get painted into a corner. That's not why I started this site. Getting hits has no purpose.