just reached 10,000 members in under a year (8m)

[Omega Prime]

I face a somewhat similar dilemma:

My site began in Feb. 2004. Up until December 04, we had about 1000 members. In the months that followed, we grew dramatically, to the point where we had 10,000 by June and 20,000 about a week ago. The funny thing is, it's mainly due to word-of-mouth, as the forum isn't listed on yahoo and google for whatever reasons. Still, we've got about 420K posts and over 9000 active members (within the past 30 days), but as you've said, there are forums with hundreds of members but hundreds of thousands of posts!