Android Central

If you've been on the hunt for the factory images of Android 4.1.2 (JZO54K) for the Nexus 7 or Samsung Galaxy Nexus (takju devices only), you can now grab them directly from Google. A lot of folks are still waiting for the OTA's but if you're looking to tinker around in the meantime, this would be a good start. Plus, the files are always good to have on hand just in case you ever need to go back to stock.

Source: Google