I really like Wugfresh's Nexus Root Toolkit.
Nexus Root Toolkit v1.8.4 | WugFresh It's a great toolkit and has accomplished lots of things for me with Galaxy Nexus, Nexus 4 and Nexus 7. Not only for rooting, but the stuff that comes afterwards.
Be warned though. To root you need your bootloader unlocked. Unlocking your bootloader will wipe out all your user data. So if your bootloader is locked you will have to reinstall media files etc...
However, the toolkit can help with a backup and restore.