yup ... virtual hosting ...
win2k does it through a thing called "host headers" -- inside every http request, the url is requested from an IP; the serving program [apache / iis] determines what particular site is requested and correspondingly sends it out. Only downside of this is that if DNS dies, none of your sites work at all [even by IP]; if you surf to
http://YOUR.IP.GOES.HERE the url request would be for YOUR.IP.GOES.HERE, which, of course, is not a site hosted by you [unless you can register 4 octet domain names now].
So yes, you can ... blindingly easy in IIS, unsure of complexity with apache/*nix
randal