rc.conf and /etc/rc.d/network must be reworked to support profiles. Something like this:

profile "home"
{
eth0="dhcp"
gateway="stuff"
}

profile "work"
{
eth1="some wireless stuff"
gateway="other stuff"
}

And on boot, might be an idea to ask the user like this:

Please select your networking profile:
1. Home
2. Work

and then the user must press 1 or 2. If the user won't respond in 3-5 seconds, pick the first one. Well, it's a bit hacky I know, but it's needed... People move laptops from home to work to friends all the time these days...