Campaign Cartographer - Campaign Cartographer is the leading map making software for games (RPGs, miniatures and wargaming).
Tabletop RPG Map editor 2 - RPG Map II is a “tabletop RPG” oriented map maker, created with the “keep it clean & simple” philosophy in mind.
Roll20 - Roll20 is a suite of easy-to-use digital tools that expand pen-and-paper gameplay.
Dungeon Painter - Dungeon Painter is a free powerful encounter map design tool.
Dungeon Map Doodler - Dungeon Map Doodler is a free to use drawing tool accessible from any web browser. Easily create maps for your favourite tabletop RPGs in minutes!
Dungeon Scrawl - A dungeon scrawling tool by ProbableTrain