Campaign Cartographer - Campaign Cartographer is the leading map making software for games (RPGs, miniatures and wargaming).
Fractal Mapper - With Fractal Mapper, creating worlds has never been so easy!
Dungeon Tile Mapper - Dungeon Tile Mapper is a web based tile mapping tool that includes many official D&D tile sets.
Inkarnate - A free-form map editor for role-playing games, focusing on overland and continental maps.
donjon.bin.sh - Freely accessible online collection of random generators for tabletop games.
DUNGEONFOG - Online authoring tool to draw rpg maps & dungeons, create dynamic notes and share your maps online. Create dungeons, world maps and more with the easy to use map editor and create your game master notes dynamically.