Of course, if you're into measuring things and knowing with your brain that you've got the right proportions, you'll probably be fascinated by Dürer's book Underweysung der Messung (1525), which includes 22 pages about the letters and their proportions: it's available in a mouth-watering CD-ROM version from Octavo Editions, at $40 on its own, or as part of their Graphic Arts Bundle with Geofroy Tory’s Champ Fleury (1529), Giambattista Bodoni’s Manuale Tipografico (1818), and Owen Jones’ Grammar of Ornament (1868), at $132 (Jan 2006 prices).

Albrecht Dürer		Geofroy Tory	Giambattista Bodoni	Owen Jones

I'm too late to do a computer version of these wonderful forms of Dürer's, Terry Wüdenbachs of Liechtenstein has beaten me to it, but if I refine my technique quickly enough I stand a chance of being first with some of the others ;-)