Me, I'll probably repost my usual: my account of what I saw and did that day. Look for it a bit later this weekend. I might take my kids down to Centennial Park for some of the reading of the names of the murdered. Certainly not the whole thing, as they'd never sit still for it, and besides one of them has a soccer game. I'll block out an hour, maybe.
Other than that, I'll probably trawl through some archives of that day in 2001, including some of my own usenet posts. Just so I don't forget...