I just used Carbon to backup all the app data on my N7. Basically install Carbon on pc, Carbon on Android, then you gotta install the google adb drivers (I had to, at least). To do that, open carbon for pc, at the bottom of the little window you'll see a clickable link that says "you may need to install drivers". Click that, then on the webpage it opens download the "Google drivers for Galaxy Nexus, Nexus 4, Nexus 7, Nexus 10". The linked youtube video will show you how to install them (except you install from the .zip file downloaded on that page, not from the Android SDK as the video says). You must extract the zip file, the .inf driver file is inside. Then you fire up carbon on PC and the nexus, plug it in, and you should be ready to go.
Make sure you copy all the backed up data from the "carbon" folder on your nexus to your hard drive before you unlock it. You wouldn't want to back everything up and then end up wiping that backup. The you can just copy over any other folders you want to save like DCIM, Downloads, Movies, Music, etc. All those can be copied right back over once you unlock. The "carbon" folder needs to be copied back over, and then restored by opening carbon and choosing to restore your data.
Good luck!