Maybe it's like Eschalon: Book 1? In that game you had a mapping skill. If you had no points in that skill, you had no map. If you had a few points in it, the map looked barren and like it had been drawn by a three year old. But the more points you spent on the skill, the more detailed your map became, filling out with colours and names and stuff.
Best. Skill. Ever.
That's pretty cool. You can also draw you own map in the DS game Etrian Odyssey.