Is there the equivalent of the "Hello World" program for GIS applications?
I am looking to become more familiar with the development of GIS applications. What are the popular (and free/low cost) tutorials and/or sample applications that would help someone get started? Are there any books that you would consider essential for beginner GIS developers?
You could start with some basic desktop mapping software like uDig or Quantum GIS. And download some Shape files.
From there you might want to take a look at PostGIS. For web development start with MapServer and OpenLayers.
Would also be worth taking a look at the book Mapping Hacks.