said by file:Web servers need an IP address... now, you can front many of them with a virtual host aware solution that forwards the traffic accordingly but if your ISP doesn't support that and you have no dedicated IP... you are screwed. The same applies for other protocols. It's *possible* but not feasible.
A web server needs one IP address (unless you're hosting a secure site), and every major web server software has supported virtual hosts for ages (decades, in the case of Apache?). No ISP support is required, since your ISP is just a dumb pipe.