MST3K tangent. Loved it. Knew nothing about it. Was watching late-night TV, turned to it randomly, and five minutes later, I was rolling off the couch, laughing. "Tommy? Can you hear me?" "Can you feel me near you?!"
Facebook tangent. I got on for business contacts. Friends and family friended (the evolution of language: Facebook has made "friend" a verb) me en masse. I was keeping up on everyone, but it was just taking too much time. Haven't been on it for three months now. Downside: About a week ago, I found out that a beloved colleague had died, one of my true hero figures. It was too late to send anything for the funeral. I let some other people know, and they said, "Oh, we already know. It was blowing up Facebook two weeks ago. We figured you knew too."
It's part of the human conversation circle as much as anything else now.