With an OTA on the horizon, I know a lot of people are gonna be looking for stock files for their Nexus. It always happens, so I figured instead of feeding you I would teach you how to fish
You'll need Linux. You can install it, run a live CD, or use Wubi and install as a Windows app -- any way will work.
You'll need the factory system.img for your device. You can find it inside the factory image tar file provided by Google.
You'll need the file attached to this post.
1. Create a folder in your home directory named restore
2. Place the binary that's inside the attached zip file in the restore folder
$ cd ~
$ mkdir restore
3. Make sure the binary file is executable
$ cp path/to/the/file/simg2img ~/restore/simg2img
4. Place the system.img file from the factory images in the restore folder
$ chmod +x ~/restore/simg2img
5. Make a folder called GNEX
$ cp path/to/the/file/system.img ~/restore/system.img
5. Change to the restore folder, and prepare the system.img for mounting
$ cd ~
$ mkdir GNEX
6. Mount the system image as a folder
$ cd ~/restore
$ ./simg2img system.img gnex.raw
7. Open the GNEX folder with your file manager, get anything you want from it.
$ sudo mount -t ext4 -o loop gnex.raw ~/GNEX/
8. When you're finished, unmount the image
$ sudo umount ~/GNEX/
Note that this only works with ext4 images, and has only been tested on images from Google for the Galaxy Nexus, Nexus S, and Nexus 7.
Thanks zhengkarl for the source for the simg2img binary