I always found his contributions (here at Math-teach as well as at other fora) to be thoughtful and most thought-provoking. I had long intended to write to him personally to tell him just how much I appreciated his writing. I feel most depressed that I kept putting this off - now I shall never be able to do that.
Do you have any idea of how it came to be that he died at such a young age? The online obit says nothing about this.