I've got two domains, each with a separate web site and mail server. I also have a LAN masqueraded behind a firewall.
Right now, this is using 3 IP addresses. If I can get to 1, I get a gold star ($30/mo cheaper DSL service :-)
I know I can do port forwarding to get one of them pulled in, but that doesn't really get me anything. Is there a more sophisticated version of port forwarding that'll deconstruct packets coming in on a given port (like, say, port 80 :-), figure out which are trying to reach which domain name, and then forward them along to different locations depending on the results?