I've implemented maps in two games I've created/am working on. The first game is a single-room puzzle with four rooms. Er... anyway. The maps show the path of a little robot that you have to program to go pick up an item, as it goes through the map. Granted, it took a lot of fiddling to get an animated, autogenerated ASCII map to work in TADS 3, but the result is quite impressive. To me, anyway. It fits nicely, plays well, and looks good. However, it doesn't show the player on the map - just a little robot. Once you actually get inside the room, you realize all the walls are very short, and thus the entire map is just one 'room'.
The second map is actually even more complicated - it's a "pixelated" color map, put together out of an autogenerated outdoor room map. Each "dot" on the map corresponds to a single room; however, like the country maps it imitates, it doesn't care where "house" rooms are. It just maps the entire "house" as a gray block. Desert is yellow, ocean is blue, lakes are blue, jungle is green, grassland is tan. Meanwhile, the game itself is more of a rouge-like, though with a much less detailed map - more like a map you'd carry, rather than an overhead view of your exact surroundings. When you're in a house, the X that marks your spot doesn't move until you leave. While I like the way it looks and works, it's not how I'd suggest building a game. This game has thousands of rooms... great for rougue-likes, terrible for anything else. Really, really terrible.
That being said, a well-designed map is awesome regardless, even if it only barely corresponds to the game.