I'm with Jason on this one regarding using separate email addresses for different areas of ones life.
Twitter is only really useful when on a mobile device and I never look at it my PC but I find tweets from the local police giving details of traffic, road closures etc very useful. I have followed ME since it started but in all honesty cannot say I would miss it if I was not a follower.
I do think there are just too many social media sites, I occasionally look at FB and have seen suggestions by disgruntled Yahoo group members to move their group to FB. As bad as Yahoo is I just dont see how FB would be better as I find FB really lightweight and somewhat transient.
Ian P