Simply, a small radar that shows the player's position relative to a map.
Method 1:
Slightly updatable.
The map would update based on where road bricks are ONLY. This might look ugly unless extensive coding is done because roads are used in many ways.
How ACM city would likely look in this method:
Method 2:
One large image is used that is not updated in game whatsoever.
Instead of generating the image, someone would simply put the map image in the .zip folder and it will show it. Although it wont update based on brick placement, it would allow people to make better looking maps. One pixel in the map would equal one stud ingame. (when at normal zoom level)
How ACM city would likely look in this method:
