If you don’t “get” Facebook and Twitter, read this NY Times article
lsvp.wordpress.com
lsvp.wordpress.com
OR they got bored and spammed to death such that they stopped using facebook. (My personal experience)
I think that adding the feed and the apps forced me to use Facebook the way it was meant to be used. I got rid of all but 70 friends, people I cared about, and suddenly it became a very productive way to plan out events and talk to friends in the middle of class. No spam, no feed updates that I don't care about.
The article explains how it works -- ambient awareness and all that -- but it doesn't explain why I'd want that, if I'm not one who already "gets it". Why do I want 1000 asymmetric "weak ties"?
I have noticed that the people who use twit/book the most are those with cell phones. If you don't have a Blackberry welded to your hip, tweeting "I'm making a sandwich" has way too much overhead.
And why would you want to "constrain your identity"? The ability to revinvent yourself is a great gift.
Also, it gives people a conversation starter with me, usually with the word "What the hell?" beginning it.
On a more serious note, there was a link here to the "best" 100 Twitter accounts. That might help. Or not. I dunno: I stopped using Twitter.