Unetbootin is a program that allows to create units booteables in USB, of different distributions of Linux. In case you do not have a CD or DVD reader (for example in netbooks) and you can not use bootable discs, you can use this alternative, since the application is responsible for downloading the ISO from the selected distribution.
The ISO is recorded on the USB stick or USB memory so that, from that unit, you can install Linux, and in addition the application is responsible for generating a boot loader using Syslinux, to decide whether to start the Windows PC or any of the Installed distributions.
Unetbootin has support for Ubuntu (version 11.10 and earlier), as well as the latest versions of the following distributions: Debian, Linux Mint, openSUSE, Damn Small Linux, SliTaz, Puppy Linux, gNewSense, FreeBSD, NetBSD, Fedora, PCLinuxOS, Sabayon Linux, Gentoo, MEPIS, Zenwalk, Slax, Dreamlinux, Elive, CentOS, Mandriva, LinuxConsole, Frugalware Linux, and xPUD. The complete list can be consulted in the official site of the project.
This application can be run on both Windows and Linux. It requires a formatted USB memory, run the program, and select any of the supported distributions. It also requires about 3GB of disk space to create the partition where the distribution is to be installed.
UNetbootin allows to store several useful applications booteables, as is the case of Parted Magic, to manage partitions; And also some antivirus such as Dr.Web Antivirus, F-Secure Rescue CD, or Kaspersky Rescue Disk.
UNetbootin 585 is the latest version, updated in July 2013, of this Linux installer that can be downloaded for free. Works for Windows, Linux and Mac OS X.