Wikipedia
Pyxplot
Pyxplot is a free software command-line graph-plotting and vector graphics package. Its interface is similar to that of gnuplot, but its graphics engine is optimised to produce output in a style appropriate for inclusion in academic journals. The LaTeX typesetting system is used to render all text labels, making it easy to annotate graphs with mathematical expressions. In addition, Pyxplot has many more flow control constructs than gnuplot, making it much easier to perform batch operations.
Pyxplot is available for free download under the GNU GPL.