Venn diagrams are a handy way of visualising, to quote Wikipedia, ‘all possible logical relations between a finite collection of sets.’
They can also be humorous. Here’s a popular favourite.
I also like this one:
Many of the arguments/topics covered on Harry’s Place and elsewhere in the blogosphere lend themselves well to Venn diagrams. Mohammed Amin turned to them to illustrate his thoughts about the relationship between antisemitism and antizionism, and Dru Marland produced this in response to the Julie Burchill/Suzanne Moore furore. (A)theism is a good example of a topic which can be usefully represented by a Venn diagram.
Do Harry’s Place readers have any other favourite examples?