Often I've been looking at my map and found the place I want to go. But there is no functionality to mark the location so I can easily see it later or view it on the minimap. I suggest a simple system of clicking to add the marker with some text and optionally an icon which is displayed on the minimap. The player can then remove it when done. This would be useful for things like marking ore patches you intend to go to, biome chests in the Dungeon, or even just making the map feel more organised.