Allow diffs to be annotated, much in the same way GitHub (or Git Blame) allows you to. This would be a major win for nearly every code-review-based process out there.

These annotations would need to be persisted against the original files somehow. Possibly within a '.zip' variant containing both files and the annotations.

This is related to http://devart.uservoice.com/forums/93035-codecompare/suggestions/1332369-diff-reports. If the results of the review sessions could be exported to PDF that would also probably work.