In looking for other famous family trees, I came across someone who had compiled a tree for Winston Churchill with more than 6000 people in it. He graciously sent me a GEDCOM file of this tree, and I have included it as one of the samples in the (d3) family tree visualization project I am playing with. A screenshot is below. I had to cull people born before about 1300 because of (apparent) needed optimizations in the processing steps. It's kind of a mosh pit prior to 1300, anyway - the "widest point of the Ancestor Cone happens for most of us around 1200AD" (info via Tim Urban's awesome article on ancestors/pedigree collapse).
GEDCOM file courtesy T. Dowling.
Interactive Visualization available at