At the 2012 Bay Area Maker Faire, Make Magazine's blog took pictures of 23 unique 3D printer designs. Unfortunately I have yet to find write-ups!
As I can find it, I hope to capture information on each of these on my 3D printers page.
To date, the most complete directory of 3D printers I have found is here, from 3Dprinter.net. The director is broken down into the categories of personal 3D printers, commercial 3D printers, 3D printing services, 3D modeling software, free 3D models, and 3D scanners and scanning software.