How to Use Your Mac as a Server:
Turn your Mac Mini into a server! Yes, that's right, with a little know-how and a little spunk, you can turn an inexpensive Mac Mini computer into a server to provide services over you network. You won't even need the Mac OS X Server, just the Mac OS X Client, so there is no extra software to buy, just the Mac Mini and it's operating system.
This video tutorial from FreeMacBlog and MacMiniColo will show you how to configure two IP addresses for your Mac Mini server. You should already know how to host multiple websites on one Mac, but that assumes you want them all to have the same IP address. Sometimes, you'll need multiple IP addresses for instances like installing a SSL Certificate. This video shows you how to have two IP addresses on one connection.