Is it possible to use Samsung Galaxy Nexus as a bootable USB stick? I want to install centOS linux distro on my desktop, which does not have a disk drive. Moreover, I posses a 4GB usb stick which is insufficient for installation. I need a usb stick with atleast 8GB to install centOS. 

However, I've Galaxy Nexus which has lots of space. So I was wondering as to can I use it as a bootable USB stick?
There is currently an application on the Google Play Store called DriveDroid that should be able to handle that task. Please note that it needs a rooted phone.

After you install the app, it's a pretty straightforward process. If you need a helpful guide, this How-to by LifeHacker should help.