Nine years ago I retired to my hotel room to practice my presentation for the conference I was attending at Virginia Tech. It was on some variant of Resin Transfer Molding I think. I turned on the TV to take a break and found out the world had changed. I went downstairs and everyone was just standing in the lobby watching the news.
Suffice it to say I didn't practice after that and my presentation sucked. No one particularly cared though. I think the biggest collective tragedy in my lifetime probably takes the cake for worst intro act ever. Public speaking got a lot easier after that.
Oh and I'm with most of the gunblogosphere, why the hell is there still a huge hole in Lower Manhattan? The best tribute we could give those people is putting up something on that site.