What about the idea of carrying your operating system whereever you go? I am not talking about bringing your laptop everywhere you go, instead use your pendrive to carry your linux distro. Not simply the live distro, you can carry your operating system with all your configurations, favorite desktop background and personal files. We can call it as a persistent installation since the pendrive linux can not only used as a means for installing linux but also it can retain the changes you made (similar to a linux installation on a hard disk). In simple terms if you store a file on the desktop or installed any new application on the pendrive ubuntu it will be there next time you boot from that pendrive.