Personally I find map-making, in the broadest sense of the term, to be poorly developed form of illustration in most journals. There is however at least one journal that takes the matter seriously!
Cartographica: The International Journal for Geographic Information
"An official publication of the Canadian Cartographic Association , Cartographica provides a forum for the exchange of original perspectives and innovative findings in the production, design, use, cognitive understanding, and novel applications of maps in arts, cartography, computer science, economy, engineering, geography, history, medicine, health, and surveying."
This may be a journal where not only authors but journal editors can look to get ideas for effective design and use of maps.