I've been learning about the proportions of the face recently and was just so amazed by its' design and how everything fits together and is a part of each other that I started to wonder what it would look like to follow each proportion exactly and here is the result. I've included the rig and the base retopologized head in the blend file. The rig is grouped into three different detail levels to provide some organization and also the text is in its' own group, so all of the text can be turned off together. Also, when I was doing the project, I decided not to spend the time doing a great retopology job on the neck since it wasn't going to be seen and the mesh resolution was so high that it didn't matter anyway, but you may have to fix that if you decide to use the head in a project. Even though some of the proportions change a bit from person to person, the rig does provide good guidelines as well as a very good checklist of things to look for when sculpting. If anyone has any proportions I may have missed, please feel free to share as well.

As a side note, the first image is what is actually in the blend file. The other four are part of the final image I made. Also, if you would like to see more about the workflow I used to make it look like clay, I made a few notes on my website found here: http://johnperkins.wix.com/john#!proportions/cup5
It can also be seen on Blenderartists here: http://blenderartists.org/forum/showthread.php?381652-For-You-Are-Beautifully-and-Wonderfully-Made-All-the-Proportions-of-the-Face