For me, it has to be the passing of SmallFry.
I have been quite active on a number of forums online for more than 12/13 years, yet I have never witnessed the demise of one of us, be it out of old age, or sickness, or unnatural. Never.
Seeing that thread that day, reading the title in the list if my unread threads, I thought someone was having some fun with Nate, maybe someone ranting at him, or having a play with him for something he did and they were going to kill him for it.
After reading mkawa's post, my heart stopped, I didn't know how to react, I was speechless, almost thought I was dreaming or reading it wrong, I shook my head, and then reread what had been posted. I didn't know Nate nearly well enough, maybe not at all, however having read his many helpful posts, I knew how much he meant to this community or rather. How much this forum meant to him.
Irrespective of that, I think if mkawa had found out the same about someone else, someone who hadn't been as integral or active on the forum, my reaction would have been just about the same, because I am a sentimental and emotional person and attach myself closely with any forum I join and its members.
This is a memory that is sure to leave a lasting impression in my mind, and in some ways triggered the keyboard enthusiast inside me and I became active here, and I in someways feel that is my biggest tribute to SmallFry. I am sure wherever he is he would be happy to know he gave GeekHack another member.