Why don't distributions provide an image that can be dd'd onto a USB stick? I'm sure I'm not the only one who finds USB mass storage infinitely more convenient than CDs nowadays. Sure, they provide a USB image creator, but you have to have a fairly standard (and graphical, last time I checked) Linux installation first. And sure, you can extract the files and make one yourself, but is that really necessary?
This goes for both Ubuntu and Fedora.