I think that one of the most useful developments of the past couple of years has been bootable USB sticks. Not just "LiveUSB" sticks, from which you can actually run Linux, although those are wonderful too, but just plain old bootable distribution installers. They keep me from having piles of used CD/DVD discs around my desk, save me time in creating and booting the installation media, and even give me a bit better conscience about not continuously using discs for Alpha/Beta/RC/whatever releases one or two times and then tossing them on the pile.
Several of the major distributions have had their own way of creating USB stick media for some time now. Ubuntu has their "Startup Disk Creator", which also works on derivatives like Mint, Jolicloud and such; Fedora has a "LiveUSB Creator". Taking another approach, several of the distributions use "hybrid" ISO images, which can be copied directly to a USB stick (with dd or equivalents) to create a bootable USB stick - Fedora, openSuSE and others do this.
But what about the other distributions? I recently wanted to try out Linux Mint Debian Edition, and as it is not derived from Ubuntu, it is not compatible with their Startup Disk Creator. Of course I have also recently been installing PCLinuxOS 2010.7, which as far as I know also doesn't have its own USB stick creating scheme. What to do? Well, I noticed in the Mint Debian release information that they had made sure that it was compatible with the UNetbootin utility to create a bootable USB stick. So why not give that a try...
The UNetbootin executable can be downloaded from SourceForge, for either Linux or Windows. That's easy enough... then just run the downloaded file, and you get a window that looks like this:
There are two ways to use it, depending on whether you have already downloaded the ISO image you want to use or not. If you haven't, UNetbootin has an impressive list of distributions that it knows about, and it can download quite a lot of different versions for each of those distributions. Select what you want from the lists at the top of the window, and you're ready to go. If you have the ISO image already just use the "Disk Image" fields to point it at the one you want, and you're ready to go. UNetbootin will identify whatever likely candidate(s) it can find for the USB stick target, you select the one you want, click "OK" and in 5-10 minutes you have a bootable USB stick! Zowie!
When you boot the stick (I hope that I don't really have to say here that this step depends on your computer being able to boot from a USB port...), you'll see a pretty typical string of Linux boot messages, and then a boot selection menu. The top item on the list will be "Default", which will usually get you whatever kind of boot result you would have gotten from booting the ISO from a CD/DVD drive - it may be a "Live" boot, an installation boot or whatever. From that point on, it should be the same as running the image from a disc.
In the past two weeks I have used UNetbootin to install Linux Mint Debian Edition and PCLinuxOS 2010.7, and both worked without a hitch. The only distribution that I have had any trouble with at all was Debian GNU/Linux, because its boot/install script explicitly tries to mount the installation CD media, which of course doesn't work.
One last really nice thing about using UNetbootin - you don't have to worry about media size, and distinguishing between what will fit on a CD, and what will have to go on a DVD. Well, unless you are like me and still have some old sub-gigabyte USB sticks around...