Engage, don't Offend

Over at Slides that Stick they pointed out that some images may be too emotionally charged to use. I pointed out that you should be wary of unintended emotional connections, but you should also be careful with intended emotional connections.

The image to the right is of the former World Trade Center towers with two planes flying over with the caption "Learn to Anticipate" below. This is a powerful, and emotional issue, and should only be used for a point that is equally powerful and emotional. I'm not opposed to using strong imagery, but it needs to be appropriate. For example, I might be willing to show a picture of a concentration camp during the holocaust in order to illustrate the deep emotions of Lamentations. But something like that shouldn't be used in any way that could be perceived as flippant or joking.

How would you use strong, emotional imagery?