In this example, I had a machine with no CD-ROM that I was trying to install Ubuntu on. I had another laptop handy with Ubuntu on it so here we go. I chose the Ubuntu 9.04 i386 cd .ISO image [ to download. to use for installation.

The installation is extremely simple. Just install the portable linux package which is easily installed in Ubuntu.

Once installed and launched you will simply be asked to choose an iso, if you've downloaded the iso just simply choose it from the local location. Once you've done that choose the destination usb drive. For me the software picked up the only usb drive which was actually 3.9GB formatted. I was highly impressed, it showed up as /dev/sda6 or similar in the menu. I simply choose your media installation from the drop box. There is one last option where you are able to choose the amount of space left available for personal storage, this is because if you're doing this with a live-cd which in my case the installation media is live, by default, Portable Linux makes the usb environment persistent so that changes are automatically installed. So applications, themes, fonts, media, etc are saved. Once you've chosen an adequate amount of space to save for use, simply choose install.
My first attempt at this failed, I think this was more to the fault of my Ubuntu installation. Once the process starts, it shows you what is happening. One of the first steps is to format the drive, well once this happens, gnome automatically mounted the new installation and it failed. I just simply reattempted the installation and since it was already formatted it went on with no issues and I have tested the usb stick and it is working great.

Before I started to do this I looked around for a tool to do this with and there are several commonly used apps out there for this. The one thing that I noticed is that many of them still require one step of this or that after or before installation or maybe do not offer as many options as the application that I chose to use. Portable Linux seems to just be over the top for this, it offers great functionality over many other tools for making a bootable usb linux key from a .iso file.

Here's the project's home:
http://rudd-o.com/new-projects/portablelinux

Many of it's features include:

- Remember your customizations: What's more, if your distribution supports persistence, the files and settings you edit on your live Linux distribution are persisted across reboots.
- Install any distribution, on any distribution: Unlike the competition, it runs on any Linux distribution. On top of that, you can install not just Ubuntu, but any distribution that uses Casper as its LiveCD technology. So if you have Fedora and want to create a live removable drive with Debian, no problem, Portable Linux can do it.
- Rescue systems and run other OSes: Since it uses GRUB (the GRand Unified Bootloader), you can:
* easily add memtest86+ and MS-DOS to it (handy for those BIOS updates),
* boot a Linux or Windows machine with a damaged MBR (master boot record), then subsequently repair it,
* boot any operating system installed in any of the disks in your computer; and even
* boot your Linux operating system using the root partition on your hard disk.
-Access all your files saved on the USB drive: Finally, you can access the area used to store your files just fine from within your Linux distribution. In that manner, you can create your live Linux distro, install a couple of codecs and applications on it, put a bunch of MP3s or movies in it, and you've got a complete multimedia center on your pocket!