Hexographer was built from the ground up to let you make maps in a few specific styles quickly. By eliminating a large number of cumbersome options general image editors & computer-aided-design (CAD) programs use, Hexographer lets you make a map in a tenth of the time it takes just to learn another tool.
And please check out the sister applications Dungeonographer (for dungeon and building interior maps) and Cityographer (for city maps and auto-populating the buildings with residents, price lists, and more)!