Well, I lack the eloquence of many of the preceding posters, so I'll keep it simple...
My alarm was set to a news station. I woke up in the middle of a sentence about a plane hitting the World Trade Center. I thought I was having a nightmare and hit "snooze".
When the radio went on again I was fully awake. I ran into the living room and turned on the TV in time to see the first tower collapse.
I called my folks, who live in NJ, just to make sure they were all right. My mother was trying to reach her sister, who lives in NY. She was fine. My wife was worried about a friend of hers who lives in DC and works at the Treasury Department. She was also fine.*
I drove to work in a bit of a haze. For some reason, our medical group actually bothered to have a business meeting, although I don't remember that anything useful actually got accomplished.**
I spent most of the day logged on to these very message boards, lurking, reading the posts from Triple H and Chairman Kaga, whose work I greatly appreciated. I remember becoming enraged at another physician who called me that day to whine that I hadn't completed a report on one of his cases. I remember being largely incapable of getting any work done, so a friend and I eventually took a long lunch break in a nearby park under a treacherously serene blue sky.
I remember feeling both profound grief and cold fury. I remember hearing the (probably overly-emphasized) reports of a few Palestinians dancing in the streets chanting "God is great!" and telling my friend that this was why I couldn't believe in any sort of God, because everyone in the world thinks God is on their side. My friend, a devout Christian, wisely said nothing.
But I also remember that in the midst of the carnage, there were moments of such grace and selflessness and courage, from the rescue workers at the WTC site, the passengers on the plane that crashed in Pennsylvania, and yes, the folks like Triple H and Chairman Kaga on these messageboards. And I am thankful for that.
I've rambled too long about this. Sorry.
-- Pazu
*My wife later told me that her friend at the Treasury Department first realized something was wrong when she was watching the international market and saw the dollar drop suddenly.
**Our group generally doesn't accomplish anything useful at business meetings anyway, so this wasn't unusual.