You might want to consider doing some more Spanish civil war decals; it's a relatively unexplored modeling niche. How about some signs, posters, Nationalist and Republican graffiti, and maybe even some large advertising of the sort that was painted onto the sides of brick buildings. Another suggestion: if you can find pics of Spanish streetcars during that conflict, you could print some decals to allow modelers to use the excellent Miniart tram in their SCW dioramas.