Commemorating Sept. 11

I was very glad to read that John McCain and Barack Obama put aside politics today to commemorate Sept. 11.

Here is a news archive of that terrible day.

Where Were You compiles everyday people's memories of Sept. 11.

While my children are still too young to understand the events of that day and I don't want to scare them (I spent much of my youth terrified of a nuclear attack by the Soviet Union and won't subject them to similar fears of terrorists), I am interested in books about Sept. 11 geared toward children. I'd like to read some first and decide the age-appropriateness, as it's a tough subject to address with kids.

Any suggestions?