I searched and I didn't see anything for the word "overlay" in here.
I'd like the ability to draw graphical overlays on the map such as colored transparent circles, lines and arrows. It might just be overly complex for a game but I always play Insane maps with a lot of races and oftentimes I lose things such as planets with big manufacturing boosts, my capitals etc. I also like to scope out enemy planets before invasions and it'd be nice to not have to re-check them every turn (I usually hit key planets in their territories rather than planets on the edge).
I currently use rally points for this very purpose but they get lost in the seas of ships and other icons. If graphical overlays were a $5 add-on I would purchase it.