My wife knew about this site, and she tells me that for a long time growth was somewhat hampered by their inability to scale. They had to manually allow users into the site in chunks (you email them your info, they email you the following Friday when you can finally post on the boards). He obviously had some hiccups, but he managed them well and learned as he went. That's an admirable quality.

I completely agree with patio11's comment about the other half of the population being under-served.