Projected maps

[MacLoued]

I am attempting to project my maps on a vertical surface. What kind of program can I edit on the fly while keeping a full screen and adding/subtracting tokens?

[Cycada]

I would imagine Roll20 could fit the exact description of what you want, or if you want a manual way of doing it: flip your projector (safely) so that it is facing down at a table surface and just use mini's on the projected map.