Mapmaking and in-game currency.

On HeroesPortal, this is sometimes practiced: there are author(s) willing to draw a mini-map (i.e., the drawing itself) or create a beautiful rendering of the terrain in exchange for the local virtual currency (arroba). They also regularly hold a contest for the best new maps, and the winners are awarded arrobas.
So, if you have ideas and are willing to draw or spend some money, visit their forum section "Mapmakers' Table".