My use cases are similar. Here are some of my thoughts: * Facebook: Photo and video sharing with friends and family. That's 80% of it. 15% is hearing updates o

My use cases are similar. Here are some of my thoughts: * Facebook: Photo and video sharing with friends and family. That's 80% of it. 15% is hearing updates on friend's lives and 5% is sharing my own updates. * Twitter: Following the thoughts of various people or subjects. I only follow a couple of real-life friends on there, most of the accounts I follow are celebrities, tech-oriented accounts, who post things I like to see. The idea of being able to hear blurbs from anyone I want to (who offers them) is appealing. TBH, to me it's like an RSS feed of short blurbs. * E-Mail: Communication with the outside world, centralized around me. I try to push as much through e-mail as possible, except for info aimed at people who I know prefer alternative methods. * Chat: Real-time conversations. I try to couple this to my e-mail for convenience. So, G-Mail + G-Talk is a winner. If I tend to use Facebook for a specific contact, I try to IM them through it as well.