is it ok to use them to charge a PSP when the xbox is off?
meh, i'll probably find out before anybody responds.
they're always hot and i gave away my PSP charger because i used to have a docking station for it.

yes, although if the xbox is off I doubt you'll be charging anything. since the USB port needs to draw power from the xbox power supply which only has power when the xbox is turned on.
I wouldn't try using the xbox for anything serious while doing it though. It's safer to have a usb hub and charge it that way..

if you have a new generation xbox that is (the one with USB ports in the back)

if you have an older xbox then the answer is probably not.

um, all of my xbox 360's have been capable of being turned on by a wired controller, and i already know that it is charging the PSP, just don't know if something might explode.

hmmm, well, it appears that my original PSP might be dead. well, i ain't figured how to get it to turn on yet, maybe it's just a woman. the power light has been blinking funny for like a month, but i ignored it. it stopped playing my music today, but the power light said it was still on, bah, i dunno, it don't worky no more.

nevermind, it's working again. wtfomgbbq!