I really like Gnuplot (http://www.gnuplot.info), a command-line utility for creating sophisticated graphics. It's in line with Red and Rebol's philosophy: Keep It Simple (KIS). Here's an example:
#!/usr/local/bin/gnuplot -persist
set hidden3d
set isosamples 50,50
set ticslevel 0
set pm3d
set palette defined (0 "black", 0.25 "blue", 0.5 "green", 0.75 "yellow", 1 "red")
splot sin(sqrt(x**2+y**2))/sqrt(x**2+y**2)
And the result:
