Nice! I'd love to see a follow-up that deals with the "Sideways Heaps" that Knuth discusses in his last "Computer Musings" lecture (on video at <a href="http://scpd.stanford.edu/scpd/students/Dam_ui/pages/ArchivedVideoList56K.asp?Include=musings" rel="nofollow">http://scpd.stanford.edu/scpd/students/Dam_ui/pages/Archived...</a>)