Auto-Updating Maps

I think it would be great to create a map that, once explored, would update the map continuously without additional user input. However, there are advantages to the traditional static map, so I think this should be a new type of map, perhaps made with more expensive items such as redstone components. This new type of map would be especially helpful on servers with massive maps that would take forever to update manually, and for "set it and forget it" type map displays where the maps are displayed behind glass.

Perhaps the map could update when a redstone signal is applied, to prevent excessive lag; alternatively, the map could be updated every time the chunk(s) that it represents are loaded into the game.