Visualize your data with gnuplot (developerWorks)
Gnuplot is a freely distributed plotting tool with ports available for nearly every major platform. It can be operated in one of two modes: when you need to adjust and prettify a graph to "get it just right," you can operate it in interactive mode by issuing commands at the gnuplot prompt. Alternately, gnuplot can read commands from a file and produce graphs in batch mode."
