Compass - Not suggesting adding a compass to the HUD, per se, but it might be nice to be added as a craftable item. Could make one, have it in your backpack and click it to use and it could tell you which direction you are facing when you use it. Rather simple and I wouldn't think it would take too much away from the game.
Cartography - A suggestion for a skill, or perhaps sub-skill. Was thinking that there are a number of written items in the game (schematics, recipies, designs) but no skill to take advantage of them other than the crafting which uses them. What if there were a skill to copy said designs on pieces of parchment or paper? Said skill could also be useful to have characters make their own maps... a lower skill could draw incorrect maps which could mess things up for anyone using them, which could be fun too.