SpriteFonts++++ - where you could select part of the text and change it's color/bold/italic (always was imaging that as a one sprite with many images (like animations in sprite)) - without using shaders.
But actually some time ago Ashley mentioned about...can't remember the name so lets call this UberSprite. An object that is a blend between Tiled Background and Sprite.
Where you could set things like: repeat texture, offset a texture, scale texture etc.. I wonder what happened to that idea.
Tilemap+ - where you could set some variables for specific cells (without using separate Array object) and maybe some easier and nicer way to make it work for isometric grids
and what newt said, all thou Path might be tricky with current SDK and editror limitations :/