The Galaxy Nexus Toolkit by forum moderator and recognized developer mskip has always been the must-have tool for owners of that device. It easily unlocks the bootloader, roots the phone, and installs CWM to get you all ready and set up for your flashing needs, and provides many other useful options.
Better yet, it was just updated to version 3.0, which does all of the aforementioned steps with one click – so, even if you’re not familiar with all that stuff but are willing to take the risk of voiding your warranty, you can now go ahead and enjoy all the custom ROM goodness the Galaxy Nexus has to offer. Should you change your mind, it also allows you to relock the bootloader and reflash the stock recovery.
Sounds good enough? Visit the forum thread, which also provides detailed tutorials and lots of FAQs to help you get started._________