I've written about Twitter before, okay quite along time ago. I'm still a big fan and find it among the best ways to learn about new things and stay on top of current developments on a wide variety of topics (and that doesn't include daily breakfast reports, at least not usually).
I use CiviCRM in several projects I have worked on for non-profit organizations. It provides a robust backend for membership management as well as event registrations and makes accepting payment (especially with Paypal's Website Payments Pro) very easy.
