Do you know how many have died in Iraq in response to the 2,998 who died on 9/11? Could it be as many as 1,000,000?
Iraq Body Count offers "documented" deaths. They readily admit that this estimate is an undercount, because many, if not most deaths simply aren't documented. But they defend themselves by saying that they are at least offering a number that must be conceded at a minimum. They have the death count at about 100,000.
The British medical journal The Lancet published a study in October of 2006 that put the death count at 655,000. The methods were criticized by conservatives, who claimed the figures were way too high. The publishers in turn offered counter criticisms.
The London based polling group Opinion Research Business published a study in January 2008 that estimated about 1,000,000 dead. I'm not aware of criticisms of the methodology. Many believe that media coverage of this study is been surprisingly limited. See for instance here.
Americans are woefully ignorant of the numbers, and yet well aware of the number of Americans killed. This was revealed in a poll that once again barely registered amongst the mainstream media, though it was administered by the AP. The median estimate for Iraqi deaths in the opinion of Americans: 10,000.