Can I share a secret with you? Something I wish had known a few months ago?
There are a lot of Ning groups out there. I've landed in a few of them. And you can't log in under more than one email at a time. Ugh. So I'm in Triiibes under one, Sales Club under another and a SAMBA group under yet another. This is a nightmare from a logistical standpoint!! I can't easily switch from one group to another. Sigh. Live and learn, right?
Another tip related to Ning. If you ever start a group, do it with a throw-away email and user name. Because if you participate in the group under your admin address, you can never get rid of that group. If someone came along and offered you money to take over the group, the only way to give them control is to delete yourself from the group. So all the work you put into the group, all your participation would be gone. Poof. Unless you're OK with that, don't participate in your Ning group under the same account as the one you set it up under.