I think doing that might be ... complicated. The credit goes to the
account that the Reader is registered to, and I don't think you can buy books for someone else with it. So unless you were close enough to phyisically meet and register your Reader to someone else's account, or they were willing to trust you to log into
their account and register your Reader (and then un-register it so you could later register it to your account), I don't know how you could arrange doing this.
