It would be cool to have a graph for the Maniphest/Ponder. You can see the proportion of open/close tickets/questions. Also the progress of a period of time.
I found a plugin implemented in another Phabricator server: https://phabricator.wikimedia.org/project/sprint/report/burn/?project=PHID-PROJ-x2wfspcmoqhkq3vrxwhc
It doesn't look the best, but it's nice.
Also a graph it could be created for every application. For example for repositories. How much code was pushed per day, etc.