I've just finished milestone for my PCB viewer
http://cuwire.io/viewee/. It allows you to browse Github for PCB designs in Eagle, Kicad and gEDA formats online. Also, if you're on Mac, you can download and install QuickLook plugin to browse local PCB files with previews.
Here is the page for visual search for PCB designs on Github:
http://cuwire.io/viewee/preview/You'll definitely face some problems, rendering is not ideal at this time.

I hope you'll find this useful.