Google has now released the Android 4.1.1 Jelly Bean factory images for certain Nexus models which allows you to return your Nexus to a factory state no matter how messed up it is. The devices included are:

• Nexus S - i9020t, i9023, i9020a
• Galaxy Nexus- yakju, takju
• Nexus 7 – all

This is relieving news for those out there who enjoy rooting and messing with their device as much as possible. You can grab the images at the source link so that you have peace of mind.

Android Developers, Android Central