I checked out Ning and searched for various topics. I didn't think that there would be so... many groups. I liked what I saw at Teacher Librarian Network . There was a group for HS LMS, which I was. And the forums would be really helpful, sorta of like the listserv used by WEMTA members, only you can see all of the forums and responses. I haven't joined this network a-c I'm not active as a LMS.
However, I've thought of several networks that I could create (retired LMS, Class Reunion from HS or college, Lake Association group). I may just join the TeacherLibrarian network and add a group for retirees. Cool site!!!