I would prefere having a portable QEMU made that would allow anyone to install the OS of their choosing rather than having a portable OS premade for them. It would be absolutly great if this QEMU used the QVM86 virtualization software (KQEMU is closed source, but QVM86 is GPL) as virtualization seriously helps QEMU. Also, if a GUI for QEMU (I reccomend QEMU manager) were to be made portable along with it that would be even better. You could preload a few QEMU portable OS's as premade, but I think that making a portable QEMU would be best of all. I use QEMU a lot, and would love to be able to take it with me. Damn Small Linux, Puppy Linux, and React OS already are made portable, but I would think it would be nice if someone wanted a portable Ubuntu, they could make one, or they could make a portable SUSE. Or a portable slackware. Or even, if they bought a liscense, a portable windows. Adding in the virtualization part is necessary for larger OS's though as QEMU alone is just far to slow. A portable QEMU alone would be enough for me to purchase a removable hard disk.