Allow users to filter elements (e.g.: cities, country borders, etc)

[Wise Melon]

Sometimes I look at the map and just want to see a particular country's borders, or just the capital cities, or the non-capital cities for that matter, but I am really unable to due to the fact that there is so much data, so many cities displayed at the same time, so many borders and different types too that I really can't make anything out. Especially the fact that the country borders are really rather faint when everything is being displayed.

So I think like with Google Earth it might be useful if there would be different categories with elements listed in them and tick boxes next to them so that one can decide which ones to show to better narrow some things down.