UNetbootin allows you to create bootable Live USB drives for Ubuntu, Fedora, and other Linux distributions without burning a CD. It runs on Windows, Linux, and Mac OS X. You can either let UNetbootin download one of the many distributions supported out-of-the-box for you, or supply your own Linux .iso file if you've already downloaded one or your preferred distribution isn't on the list.

The current version has built-in support for automatically downloading and loading the following distributions, though installing other distributions is also supported:

Ubuntu (and official derivatives)

Debian

Linux Mint

openSUSE

Arch Linux

Damn Small Linux

SliTaz

Puppy Linux

FreeBSD

NetBSD

Fedora

Rawhide

PCLinuxOS

Sabayon Linux

Gentoo

MEPIS

SimplyMEPIS 8

Zenwalk

Slax

Dreamlinux

Elive

CentOS

Mandriva

LinuxConsole

Frugalware Linux

xPUD