One of the most helpful tools in world building is creating a map. If you are an artist hand drawing a map is a great (and cheap) option. However if you’re like me and you’re drawings skills….are lacking, there are tools online that can help.
One program I’ve discovered is AutoREALM. This software is commonly used for role-playing games and it’s free!
You can download it here:
http://sourceforge.net/projects/autorealm/
More FREE map-making resources (mostly free trials)
http://www.nbos.com/products/mapper/mapper.htm

PlanetGenesis:
http://planetgenesis.sourceforge.net/
download:
http://sourceforge.net/projects/planetgenesis/

Other map-making resources:
http://www.ruraltech.org/gis/map_info/toolbox/index.asp
You could also try Photoshop or Illustrator.
One other option is Fiverr.com. On this site people offer do a variety of services for $5 (U.S. dollars). There are a few artist on there that offer fantasy world drawing.
You can check it out here:
http://fiverr.com/


