I'd definitely Google to see if there's any other site even remotely similar, if you haven't already. I don't see this as adult though...more mainstream...perhaps a personals section, along with resources, legal links, etc. If there's a way, I'd separate by areas for dads to more easily meet up with other dads for coffee or whatever....or to start their own local meeting groups (they could post pics of events, etc.) Probably different dad groups like dads w/kids who live with them, dads w/kids who live elsewhere but get visitations, and dads w/kids who never get to see them? And don't exclude gay/bi dads
