Tools, like rule-checking systems, tend to generate a lot of output. Too much output to look at once, so we usually just sorting on something like severity and/or category to focus on the more interesting findings.
Another dimension that should be considered more often is grouping findings together based on other attributes. I would like to see more tools use a "gather and scatter" approach in collapsing results together. For example, I might want to gather all findings based on the corresponding class and browse the collapsed summaries.
I have been thinking about what a visualization would do to better support this concept. One interesting metaphor is creating "piles" or stacks. I have added this new feature to NosePrints to support gathering items as stacks. The biggest problem is giving more information about the other items in the pile. You could do things like averaging, but I think jitter might produce the best results. Maybe something like the Picasa photo collage would be interesting.