PLoP is a boot manager that can be installed or booted to via just about any boot device, and allows you in turn to boot from any other boot device.
What does that do for you?
Well you can use a boot floppy with PLoP to boot to a USB on an old computer that normal can't boot to USB. You can also boot PLoP off a CD or install it as a boot menu for windows or linux.
It might come in useful if you are wanting to try out the new chrome OS on USB, or maybe just trying to boot from CD on an old computer that can only boot from floppy.
Thanks Steve for finding this and sending it on!