"Aw Dude!"

I found this link to a video ostensibly showing a "Massacre of Civilians in Fallujah", via Empire Notes and Lenin's Tomb. (The video is down at the moment, due to "exceeding available bandwidth", but alternative sources are provided and it will presumably return at some point in the future.) Questions, of course, arise about its provenance, but there is little evidence available either way. See it for yourselves and draw your own conclusions.

Defenders of the occupation might respond that those targetted in the video are insurgents and as such legitimate targets. Quite apart from the issue of whether the US has the right to bomb a country it is occupying, there is, as Rahul Mahajan notes, no evidence that the targets are any sort of threat:

The pilot does not say fighters, armed people, anything of the sort, just "individuals." And, indeed, there's no way they could be fighters, even of the most inept kind. They move slowly down the center of the road, avoiding all the buildings that could provide cover and, most telling, they clump together so that in the end a single bomb wipes them out. Maintaining distance is one of the first principles of moving around in modern warfare.

In short, if this is for real then what you see is a prima facie war crime. As I said above, draw your own conclusions.