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!
PyMapper - Drag and drop tile based mapping program.
Dungeon Scrawl - A dungeon scrawling tool by ProbableTrain
Fractal Mapper - With Fractal Mapper, creating worlds has never been so easy!
Dungeon Builder - Dungeon Builder is an Isometric Dungeon Map Maker that produces beautiful, high resolution maps...
Tiamat - Tiamat is Web 2.0 Tile Mapper; Ideal for creating miniature scale maps for role playing and miniature games.