I have a Facebook profile that I log into daily, mostly because I can get release info from different sites about new projects. I hardly ever actually socially interact on the site, mostly because people post either stupid or nonesensical information about their day. Why do I need to know you had a lousy day at work and are going to get drunk and go to bed early? Is this really what you want the Library of Congress to record about you for posterity?
That and I can kill an easy hour a day just screwing off playing the half-assed games on there just to piss off my friends to get them to beat my level/score.
I refuse to use Twitter. I turned off text messaging on my cell phone for a reason: text messages suck. Having a website based solely on the concept of text messaging is one of the dumbest things I've ever seen. No one has ever said anything profound or life-changing in a text, and so far Twitter has done nothing to change that. And the fact that MTV is going to pay someone $100,000 a year to be a "Twitter Jockey" is just the mercury-laced icing on this turd cake that is Twitter.