Portable Ubuntu-Runs Ubuntu Inside Windows
“Free application Portable Ubuntu for Windows runs an entire Linux operating system as a Windows application. As if that weren’t cool enough, it’s portable, so you can carry it on your thumb drive.”
SLAX – Your handy Linux OS!
Slax is distribution created for USB storages, you can download it from www.slax.org . File weights around 200mb and it gives you your OS on the go so every place you are, your OS is with you!