CSM alumnus, Scot Swan, offers Sundials_and_Linear_Algebra, which is a short (informal) writeup on the equations that are used for making standard horizontal dials. Challenge: see if Scot’s write up is consistent with the calculator at http://www.anycalculator.com/horizontalsundial.htm.
Here are more fun images from geeks like Scot:
Sunclock landscaping!
Geek clock
University of Utah CSM Group 