Generic Mapping Tools (GMT for short), is a standard way of creating maps (of earth).  It is located at http://gmt.soest.hawaii.edu/.  GMT is used by scientists worldwide to create maps.  It is ResearchGradeCode, so beware.  The ManFiles that come with the package are fairly good, and describe how to use it.  The Tutorial that also comes with it is very good, and quite necessary for beginners.  Mostly, GMT is used for ScientificPurposes, and is only really useful in that realm.

--DanielStaudigel