The icosahedral map generator lets you quickly create a world with realistic terrain. The terrain, climate and several other factors are configurable via drop-downs on the top. The size of map is also configurable using drop-downs above the map.

Below the map are hex buttons which let you change the terrain of any hex on your map. The very bottom of the map has buttons to export the data to Hexographer’s format, export the map as a PNG image, and finally load and save buttons which use the tool’s own XML format.

You can download the tool here: worldmap.jar

(Save it to your computer. If Java is installed on your computer correctly, you should be able to just double-click it to run it.)