I like having the latest Mac OS X install disk available on a flash drive, especially since it weights over 5.3 Gb.
MacWorld offers an excellent tutorial on the subject. In short, get the latest version of Mac OS 10.9 Mavericks from the Mac App Store, and use the
createinstallmedia script built into the Mavericks installer itself.
You'll need an 8 Gb flash drive this time. Format it and name it
Assuming thats the Mavericks installer is located in your Application's folder, run the following command from the terminal:
sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ Mavericks.app --nointeraction
As easy as pie. Thanks @danfrakes.