The 9/11 anniversary is just days away, and I caution everyone I work with to NOT make this into a marketing "opportunity". This is a sick example of one business that did just that. (And the backlash that they've received just proves my point.)
These guys were majorly tasteless, but even if you try to "do it right"...it's better not to do anything at all because what ends up happening is that just the HINT you're trying to capitalize on 9/11 will be a major turn off to the majority of your customers.