quickplot is a fast, interactive 2-D plotter. All it needs to do its job is a text file with x and y points in a list. If those points are longitude and latitude in decimal degrees, quickplot works like a simple GIS program, with some surprising capabilities.
This article explains how I set up quickplot to do species mapping for Australia. For most of my mapping work I use qgis and Google Maps/Earth, but quickplot is handy for quickly making simple maps and zooming in on details. With an executable size of only 453 kb, quickplot is the tiniest and fastest GIS I know.