You just need to have multiple static ip addresses provisioned to you by your ISP and then have a router whose software is capable of handling it. Every windows XP computer can have multiple static ip addresses, and I use a version of Linux called coyote Linux for my router, which supports three static ip addresses and even allows port forwarding based on which public ip address the traffic is coming in on. I'm pretty sure most basic routers sold in stores don't have this capability and you would need a pricier, more advanced model. But Coyote Linux is free. Just fyi.