Here is a small sample of thoughts on the day.

Reuven Weiser:

A few days ago, a New York Times article reported that "nearly one-third of those questioned [in a recent poll] said that their lives have still not returned to normal." "It is as if the populace has stalled in its march toward fully being itself again." I think the pollsters, and authors, are missing the point.
True, it's not normal (as anyone who knows me can tell you) for me to stand on a street corner, staring at the sky, holding back tears. But then neither is it normal for two 110-story towers to crumble to the ground, killing the thousands inside.
It is not normal for people to fear travel on bridges and in tunnels, as the article reports many still do, but neither is it normal for those bridges and tunnels to be the target of terrorist plots.
I was not "being myself" when the snowflakes falling in downtown Manhattan last winter chilled my heart as well as my bones, reminding me of the day when little pieces of white ash fell in my hair and down my shirt. But to try to "march on" and wipe such thoughts from my mind would be an affront to the memory of those whose ashes were falling on me, and that isn't me either.
So I think that, since 9/11, we need to change our definition of "normal" and our conception of what it means to be ourselves. At least until (though probably even after) we have sufficiently dealt with those, here and around the world, who would deprive us of our sense of security and dignity. Only then can we hope to truly begin our return to normalcy.

James Lileks:

The picture at the top of this page is a sliver taken from a 9/11 camera feed. It’s the cloud that rolled through lower Manhatttan when the towers fell. Paper, steel, furniture, plastic, people. The man who took the picture inhaled the dust of the dead. Somewhere lodged in the lung of a New Yorker is an atom that once belonged to a man who went to work two years ago and never came back. His widow dreads today, because people will be coming and calling, and she’ll have to insist that she’s okay. It's hard but last year was harder. The kids will be sad and distant, but they take their cues from her, and they sense that it's hard - but that last year was harder. But what really kills her, really really kills her, is knowing that the youngest one doesn’t remember daddy at all anymore. And she's the one who has his eyes.
Two years in; the rest of our lives to go.

Stephen Green:

"The purpose of terrorism," wrote the 20th Century's first terrorist, "is terror." By that measure, our enemies have failed. And failed badly.
Are you, two years later, still unable to comprehend? Be honest now. Unless you've dived head first into the bloodiest part of the heart of darkness, then, no, you don't understand. You and I here in the West, or even that vast majority in the Muslim world, can never really know what makes an educated person do what those 19 men did two Septembers ago.
But are you terrorized?
Do you live in constant, unalterable fear?
For me, the answer is: "Hell, no!"
Dread is for the weak; defiance is, perhaps, the American virtue.
I'm saddened for 10,000 children who lost a mommy or a daddy that day. I'm angered every time I see a picture of the altered New York skyline. I know a wearied irritation that this instinctively isolationist nation has been dragged into yet another world war. There is real, physical pain in my belly when that sound comes back, unbidden. You know the sound I mean – the thunk-splat of meat hitting pavement, of living people who chose to jump rather than be burned alive.
Americans are defiant, even regarding the manner of death chosen for us by others.
Now go on and let yourself relive that day, just a little.
Remember the first reports that "a small plane" had crashed into the World Trade Center. Firemen who didn't just run into a burning building, they ran up into collapsing skyscrapers. Grounded planes. The stock exchanges, closed. The doubt, the fear, the "what will they do next?" And the realization: Oh my God, we're at war. War in the Old Testament sense, when the barbarians came to rape and to slaughter.
Relive, too, the days after.
The wall of inkjet "have you seen. . .?" photos. You, me, your friends, crying over obituaries in The New York Times. Widows grieving at Ground Zero, who breathed – breathed in – their husbands' ashes.
Remember, too, our just vengeance.
Our president told us, "I hear you, the rest of the world hears you, and the people who knocked these buildings down will hear all of us soon." And they do hear us, in Iraq and in Afghanistan. They hear us, not because we used our weapons to murder their civilians, but to bring down their tyrants. From our loss, we gave them hope. The loss felt in Baghdad and Kabul is that of Sisyphus without his stone. The sound they hear is the ring of freedom. And they hear us, even if only a whisper, in Syria, in Iran, and – yes – they hear us in Saudi Arabia, too.
Maybe defiance will prove as irresistible an export as Levi's, Coke, and MTV.
Two years later, I'm still angry – and I hope you are, too. But are we terrorized?
Hell, no.

Josh Marshall:

Two years ago today I rolled out of bed in the morning, still semi-conscious and half asleep. As I walked into my living room --- the TV was still on from the night before --- I saw the second plane slam into the World Trade Center and explode in an orange and black fireball.
I'll never know whether that was a live shot or a replay of the images from a few minutes before. It was just after nine. Still groggy, I had a hard time processing what I had seen. I knew it was a big deal. But I didn't at first grasp just how big a deal.
When I sat down at my desk my girlfriend was already typing out messages on IM from her office at work. Had I seen? Where was I? They (she worked on Capitol Hill) were next, she said.
Beside watching the plane crash into the building, what stands out in my mind about those few minutes was that I asked her why she was so sure it was terrorism.
Partly --- mainly, I think --- this was because I was still only half awake and still trying to process what I had seen. I'm not sure in those first moments I was quite clear on how large the planes were. But certainly part of what was happening was that I was still for a moment living in a pre 9/11 world, where something like this was still hard to comprehend, hard to imagine.
Then she said something like: Two planes one after another in to both buildings? What do you think it is?
With that, suddenly everything snapped into place. The sleep fell from my eyes. My mind cleared. Everything was obvious.

Finally, if you have a high-speed connection, I highly recommend you watch this.
(Thanks to Will Carroll for the link.)