Let's assume the following situation: you have a computer with empty hard disk, and you don't have a CD, floppy, pen drive nearby to boot the computer from. But you have connection to the Internet.
Modern computers support network booting using PXE, but I haven't found anything regarding booting via the internet.
So, is it possible to use PXE to load an image from the internet and boot it? By having a running system (even a minimal Linux) in RAM, it should be possible to install it on the hard disk, and build up a working system from here.