How to update the Nexus devices

Download the latest stock ROM here:
https://developers.google.com/android/nexus/images
Download the latest Recovery Image here:
http://clockworkmod.com/rommanager

Unzip it and put your device into fastboot mode (adb reboot-bootloader) then type the following commands:

OPTIONAL: fastboot oem unlock (THIS WIPES THE DEVICE!)
fastboot reboot-bootloader
fastboot flash bootloader bootloader-[blahblah].img
fastboot reboot-bootloader
fastboot flash radio radio-[blah blah].img (ONLY IF YOUR DEVICE IS CAPABLE OF MOBILE DATA)
fastboot reboot-bootloader
fastboot flash system system.img
OPTIONAL: fastboot flash userdata userdata.img (THIS WIPES ALL YOUR DATA)
fastboot flash boot boot.img
OPTIONAL: fastboot flash recovery recovery.img (Use ClockworkMod Recovery for great justice!)
fastboot reboot-bootloader
fastboot erase cache
OPTIONAL: fastboot oem lock
fastboot reboot