When you use a PPTP VPN connection there is an option to send/impersonate the domain user you are logging into. That means when I am VPN'ed in I don't need to specify my domain credentials even if I'm not part of the domain, since it uses the VPN credentials. So it acts like I'm part of the domain.
Is there a way to emulate that when I'm on-site and connected directly, w/o VPN? Aside from joining the domain, of course.