You can boot Linux over HTTP with boot.kernel.org (BKO). All that users need is Internet connectivity and a small program (gpxe) to boot the machine. gpxe
program provides network booting facility. BKO allows you to boot into the following distributions: Debian, Ubuntu, Damn Small Linux, Knoppix, Fedora. BKO provides gpxe images for USB sticks, CDs, and also for floppies, i.e., you can boot from a USB sticks, a CD, or a floppy.
For more details visit : http://www.howtoforge.com/boot-linux-over-http-with-boot.kernel.org-bko