Some roleplay is sufficiently abstract that it can be carried out regardless of the internal geography of nations and their physical relationships to each other. However, in many types of roleplay, particularly war, it becomes increasingly necessary to have a more concrete idea of these.
It is very common for nations to create maps of their own nation. However, without neighbours the uses of maps are fairly limited; a great many nations end up being islands in order to elude this problem. The obvious solution to this is the multinational map: usually organised by one player and joined by request. Usually players have control of the major features of their geography, which the player controlling the map then does their best to implent to everybody's satisfaction. Another version is for one player to define just the borders and major topographical features of all the nations on a map, and then let individual players fill in the details on their own nation themselves.
Multinational maps are strong constraints on roleplay, and demand a high level of cooperation between neighbouring nations to establish consistent histories, languages and so forth.
A problem with the consistency of maps is player turnover; because nations join and leave NS at a fairly high rate, many nations on a map will disappear over time. Mapping the North Pacific (done for a while by Thel D'Ran), for instance, is a Sisyphean task. This can be partially handled by clearing vacated space to make it available for new nations and rewriting history to match (likely to get annoying in the long run), filling the space with largely-inactive puppets representing the former nation, or only allowing nations who are very active in roleplay and likely to stay around a while. A unique method of dealing with player turnover is used by Wysteria. This region incorporates "Vanishing Nation Syndrome" into their roleplay, allowing old nations to die and new ones to arrive with little impact on the rest of the map. This method may not be acceptable to regions with more stringent roleplaying requirements.
A player in charge of a multinational map is colloquially known as a Map God.
List of Extant Maps
add your map link here