I use unetbootin which is in the repositories. Once installed you need to
insert the usb stick before opening the application or it won't detect the
stick. Then you can either locate an iso on your drive or it will download
one for you. Once it is finished writing to the stick, you will have a
bootable Linux distro which is identical to the CD. It will still need to be
installed to a drive, stick or memory card afterwards just as if it was on a
CD.

To use it you need to set your BIOS to boot from USB. Most netbooks do this
anyway. When it boots you will need either another usb stick, SSD or SD card
to put the distro on (8GBs or larger). This will create a distro that you
can boot and make changes to. It works with most but not all distros.

You will have to write grub to the usb stick, SSD or memeory card where it
is installed and will likely have to manually edit grub afterwards.