Any suggestions on how to visualize the change in a score before and after an event? I don't want to plot two bars next to each other, though I realize that is the simplest. Is there something more interesting?
Depending on exactly what you want to show, here are some suggestions:
1) Parallel box-plots - this would be good if your main interest is in the distribution of the scores rather than changes in each individual, especially if you have a lot of data (say N > 30 or so)
2) Parallel strip plots, perhaps with some jittering on the x-axis. These serve a similar purpose as 1) but are better if N is small, because you can see every point
3) Line plots with a line for each subject running from before to after. These emphasize change in each person. They mildly imply that the change is continuous, although they are used often when it is not.
If as @vinux suggests, you tell us more about your data, there may be other graphs that are good.