For filled ellipse, see Re: need advice on how to create venn diagram program

If you really want to make alot of specialized, customized graphs, you are best off going with a bigger toolkit, like CairoGraphics. There is a Perl module for it, Cairo.

If you want a Cairo based graphing program, look at the examples for Gnuplot and PLPlot. They have little scripts to generate all sorts of shapes and output. You can run both from Perl.

Of course, they don't beat GD::Graph for simplicity and convenience.