Gnuplot.py is a Python module that interfaces to gnuplot, the popular plotting program. It allows you to use gnuplot from within Python to plot arrays of data from memory, data files, or mathematical functions. If you use Python to perform computations or as `glue' for numerical programs, you can use this module to plot data on the fly as they are computed. And the combination with Python makes it is easy to automate things, including to create crude `animations' by plotting different datasets one after another.