Unlock and Root Nexus 7

I found this nice guide on XDA by FadedLite, and decided to post it here as guide because it's the easiest best I could find, and a link to the original post on XDA is on the bottom.

* Disclaimer: I do not take any responsibility for anything you do to your phone, whether be brick, break, or somehow mess it up.

Requirements
1. You must have the sdk installed and you are able to access, and use adb and fastboot.
2. You must have debugging enabled on your Nexus 7.
3. Download Su here (Chainfire's thread for supersu) (Thanks Eric_Eric_Eric)
4. Download CWM here. Scroll down to Nexus 7 and choose whether touch or regular.

Pre-Steps
To make this easier, you should put the su zip on the sdcard for later.

1. In terminal, cd to the directory you have your sdk in. Then cd into platform-tools.
2. Type adb push path-to-zip/JB-SuperSU.zip /sdcard


Unlocking Your Nexus 7

To unlock your device
1. cd to platform-tools
2. Reboot to the bootloader - adb reboot bootloader
3. Unlock your device* -

fastboot oem unlock

*You will have to accept and erase all the user data on the tablet.
*You must run this as sudo in Linux


Flash Clockwork Mod Recovery
(You're still inside the bootloader)

4. Flash CWM - 

fastboot flash recovery path-to-img/CWM-grouper-recovery.img

5. Make CWM Permanent -

1. Boot into recovery

2. Go to Mounts and Storage

3. Mount /System

4. Type in Terminal*

adb shell
cd /system
mv recovery-from-boot.p recovery-from-boot.bak

If your having trouble gaining shell, try "adb kill-server" then "abd start-server". Couple of my friends had this problem, and this should hopefully fix it.
* For some people, it has been reported that you don't have to replace recovery-from-boot.bak. The flash is enough to make the recovery stick.

Flash Su

1. Go back by pressing power button

2. Install the zip in the sdcard

Reboot and your device is now rooted!!

Original tread