I do like the idea of a site like this, and I hope it does well. Belonging to a church gives many people a community focus. My wife and I are non-believers and have no "group", and have been looking for community without much luck. Not desperate for it, but it would be a plus. We belong to a community garden, but there conversations are generally topic centered. To be continued....
You touch on a very important limitation in agnosticism/atheism in current society. Churches offer social capital, where agnosticism/atheism do not, as of yet. It is a barrier that probably helps keep organized religion in place today, with likely some percentage of people attending only for the social capital. It's tough to say it, but even my parents (staunch christians) once encouraged me to attend a church function for increasing business opportunities, despite knowing my beliefs. Granted, to them, getting me to chirch at all was likely the goal.
Link to social capital/church/atheism article:
[google.com]