Looks like when the site tries to access the address you're giving it, it's getting a bad dns resolve. If you have a static ip address, make sure your firewall is allowing the rest of the world to access hfs (inbound connections). Same thing with your router. If you have a dynamic address, make sure you have a dynamic dns host that updates the dns entries for your machine.
DynDNS can help with that. Also, after setting everything up, use the self-test to verify that everyone else can access your machine, not just 127.0.0.1.