Are you a member of any online communities? Yes, I am a member of: FlyLady, iVillage, The Pioneerland Library System Group on Ning , and Flickr, among others.
Are any of these social networks appealing to you? I like Ning-it's easy to use and is sorted by interest. LibraryThing is also a kind of social network...if you squint hard enough-and I love that site. I think just about any Web 2.0 kind of site could be considered a social network--people can add their own content and comment on others' content/comments. The give and take is what appeals to me. I can have a conversation with someone who shares the same interests, but is in a completely different place.
What did you find that was interesting and that you might use later? For my LIS 768 class, the project group I'm in is going to use one of these to put together a site for the Winsted Library; a social networking site is going to play a big part. In many respects, it's almost easier than a conventional website (although I know how to hand-code one...thanks to Shane Nackerud, LIS 753 professor extraordinaire!) and it has the added benefit of enabling users to participate.
There are lots of different options out there...who knows what else I'll find now that I'm looking!