After reading the other comments so far, I think it's interesting that nobody tried to relate Pierce's Atomic Bomb poetry to poetry in response to 9/11. I think 9/11 poetry would compare most readily to Genbaku. And throwing in sources from much older (civil war, wwI/II) sources along with the newer (9/11) would make your project a more anthropological look at that type of poetic expression. (obviously civil war and 9/11 will not be japanese, but as hugh said, writing is one of those universal phenomena)
This page, from about.com, gives a list of poems about or in response to 9/11.
The Haiku I found aren't too impressive, but I guess I'm not a good resource for that since I don't like/know much about Haiku. All i did was search the Internet via Google, but maybe a more in-depth search will dig up more legitimate 9/11 haiku sources, should you choose to add 9/11 writing to your project.
There is a book by Charles Taylor about "Trauma Culture," and he describes the cultural phenomena that have occured after tragic events in history. You might want to research it and see if that will help.
I hope that helps...
~Alex