remote administration

I often find myself doing Linux tech support for various friends; since I'm behind a NAT and so are they, I can't directly ssh to their computers.  I've had many ideas, such as tunnelling TCP over XMPP, or TCP over IRC (although I'm not sure what network would let me get away with this).  Any better ideas?

>>25
you could layer it one top of a lot of things, like instant messengers
as soon as m00t notices you abuse /prog/ as your VPN tunnel, he will ban the shit out of you.