Bruce Ravel (ravel@phys.washington.edu) has written a gnuplot-mode for GNU emacs and XEmacs based on the earlier gnuplot.el file by Gershon Elber. While the gnuplot CVS repository has its own copy the most recent version of this package is available from
http://feff.phys.washington.edu/ravel/software/gnuplot-mode/http://feff.phys.washington.edu/~ ravel/software/gnuplot-mode/
For Python, Tk/Tcl, and other front-ends, check the links on
http://gnuplot.sourceforge.net/links.htmlhttp://gnuplot.sourceforge.net/links.html