One click and it turns into a red crossed X. I dont even want to write down what there is, or have multiple options. Just need that to mark "anvil here" or "uberchest, check later" in my mind.
Heh would be nice, or just once you uncover a room it automatically marks objects on the map, currently what I do is take a piece of paper and draw a square for each floor and then make my own maps of sorts so I can go back and find stuff easier.
The next patch will have an updated map that will include symbols for things like shrines, anvils, and uberchests.