A Google-sanctioned way to return to the latest stock build
Following tightly (as usual) behind the broad release of Android 4.4.2 over the air, full factory images of the latest build of Android for Nexus devices are now available. If you have a Nexus 4, 5, 7 (2012 and 2013) or 10, you now have a Google-sanctioned and supported way to return your phone or tablet to it's stock state on the latest firmware possible.
Now this isn't immediately as useful for many considering OTA update files are already available for these devices, but now if you're tinkering with things and need a wholesale reset back to stock, these images will come in handy. If you need a bit more guidance on how to apply these factory images, be sure to find your device in the forums for some great guides.