I was saddened to learn a few days ago that Seth Roberts (Wikipedia) had passed away. Andrew Gelman posts some recollections of their friendship here.
Seth and I came into contact first via the internet, although we later met in Beijing, where he had a second career as a professor at Tsinghua University. You can find some references to Seth on my blog here.
Beijing Photos 2: ... Last night I had Beijing duck with Seth Roberts. Seth has an interesting history. He started college at Caltech but transferred to Reed to study psychology. He was on the Berkeley faculty for many years but has moved to China and is now a professor at Tsinghua university. He knew Feynman and Jane Jacobs. We talked so long they closed down the restaurant around us!