I was recently following along to a tutorial to download the ChromeOS source, when it told me to use the command repo to use sync up the source to my computer. Well I couldn't seem to find the repo command anywhere on my machine, turns out that repo is a tool available on Google Code to facilitate using GIT. So you can download the command with the following commands:

curl https://android.git.kernel.org/repo >~/bin/repo
chmod a+x repo

Enjoy!