I have a Facebook account, but I’m not an active Facebook user. I use it to stay in touch with friends. I have some library friends on there, but they are people I actually consider to be friends (people I used to work with or I met at university on my Librarianship course) rather than professional associates. I don’t tend to ‘like’ or follow organisations on Facebook.
I don’t have a LinkedIn account. I think if I was job hunting it would be worth investigating further, and the groups sounds good, but I’m already doing a poor job of interacting on the online networks I’m already a part of (Twitter especially) so it’s probably best not to join any more at this stage!
There’s potential for plenty of networking out there – I just need to make an effort to get involved.