National Geographic News has a short but interesting photo gallery detailing different sites from 9/11, both on that day and now. The shots are the same shot from the same angles (more or less). I think the shots are a good testament to the human ability to overcome any situation, ultimately.
Beyond those images, the site also carries a number of other photo galleries featuring events and issues around the world. The site is worth spending a bit of time delving into. I know from some of the work Sue has been doing in historical GIS, these photo essays and galleries might someday become immeasurably valuable to historians.