Create Bootable USB for OSX pre-Mavericks
Jesus Vigo goes over the steps to create a bootable USB to install OS X 10.7-10.8 and OS X 10.5-10.6, as well as how to put multiple versions on the same USB.
I used the steps here to create a bootable Mountain Lion USB for a second partition on my Macbook Pro and it worked fine
Create Bootable USB for OSX Mavericks
For installing OSX Mavericks I followed the Manual Steps in this second article and it worked perfectly.