I was living in NYC on 8th street when it happened my sister was going to work at the time and could have been killed by debris, (a woman on the same street was hit by a piece of the plane)
The powerful have screwed over people in the Middle East and even funded the same extremists for years! The FBI testified that the foreign policies: those of manipulating the region and interfering and violating the rights of these people is what the motives were.
UPDATE: Exposing the fact that politicians and pundits are lying about "why they hate us."
Let's say you lived in an apartment building and someone in your building went around killing people in the neighborhood. Now let's say someone gets so enraged that he burns down the building that the killer and you live in. Can you now grasp the concept of two wrongs? Is this so difficult to understand? It was wrong to kill and it was wrong to burn down the building.
Yes, our policy makers have been screwing over Middle Easteners. We imposed Saddam on them for God sakes!!! What more do you need to see "we" (U.S. politicians) support EVIL and do EVIL things (like supporting Saddam which finally TODAY everyone sees as a bad guy.) If they partner with evil people, what does that make the US policy makers?
These are the specific grievances that MANY (not just the terrorists) in the region have.