If you love working in Linux then you would definitely want to have Pendrive Linux provided by Pendrivelinux.com.
Pendrive Linux enables you to install a portable Linux operating system on a flash drive or USB key. This portable Linux version can then be run from any computer that can boot from a flash device, allowing you to bring your operating system, desktop, applications, files, e-mail, personal settings, favorites and more with you. It’s like having your own personal operating system you can carry in your pocket.
Pendrivelinux.com offers various flavors of Linux: Ubuntu(various versions), Knoppix, Gentoo etc.
But before you can use Pendrive Linux you need to ensure that your PC is capable of booting from USB flash drive. Most new computers are generally able to boot from a flash drive. Older systems may require a BIOS update, or might not be able to boot from a flash drive at all. Fortunately, PendriveLinux offers a tool which can help you easily find out if your PC is capable of booting from a USB flash drive.
Installing Pendrive Linux on your USB flash drive is a breeze. Simply download the 400MB installer, extract the files to the USB key, and then click on an icon to make the drive bootable. The drive doesn’t need to be reformatted. So, you can still use it to store Windows programs. The site has very detailed tutorials for installation and so you should have no problems completing the process.
Pendrive linux is free to download and use.