I was playing with NASlite the other day and could not create the boot disk by the method explained on their web site. The bootable disk is a 1722k disk. After some digging I found some something that worked. Note: This was only tested on Ubuntu 6.06.

setfdprm /dev/fd0 1722/1440
fdformat -n /dev/fd0
dd if="image name here" of=/dev/fd0