What I like the sound of is different tools for duplicating objects. For example, a Brush duplicate when grid is turned on could allow you to 'pen in' tiles with a certain object, by dragging the mouse. If you went over an object already in that tile, it'd delete it (so it doesnt stack unnecessary tiles on top of each other), but you could turn that off for overlay tiles (treestumps on grass etc). Then we may as well throw in rubber-stamp duplication. I think these two ideas are general enough to apply to lots of types of games.