I feel terrible for all of you who knew him personally; I too enjoyed his posts as a lurker in the AA forum from time to time.
As many of the mods have pointed out who posted previously you all have lost a colleague and a friend. I have often noted to myself how some of these seemingly distant relationships become so much a part of our every day lives in a very subtle way; their absence is acutely felt in a sometimes surprising way.
Hope you're able to support one another in an appropriate if virtual way, and indeed I hope his family is surrounded by people that love both them and him as they struggle to cope with the suddenness of his unscheduled departure.