VENN.MP
This package allow you to draw Venn diagrams, properly shaded, with Metapost.
For example:
draw_venn_two(true,false,true,false) shifted (2in,1in);
draws a diagram with the outer box shaded, with the first circle but not
the second unshaded, with the intersection of the two shaded, and with the
second circle but not the first unshaded. That is, this is a picture of
the complement of the symmetric difference of A and B.
There are commands also for draw_venn_three and for completeness
draw_venn_one and draw_venn_none (go ahead and laugh; see if I care).
The license is the LaTeX Project Public License.
Jim Hefferon