Multiple Web Sites in IIS (Part 1)
Microsoft Internet Information Services can be configured to host multiple web sites. I knew everybody knew this. 
So why am I wasting my time writing this? Or why should you waste your time reading this? Well... I am just trying to make sure that you are ready for my Part 2, in which I will be discussing multiple SSL sites configuration on the same server. You should read this to understand the basics before proceeding to part 2.
Multiple web sites can be hosted in IIS using one of the following techniques.
1) Using a single IP address with different port numbers assigned to each site, meaning that you can only have one site running with the default TCP port 80. Other sites using non-default port will have to be accessed using unfriendly URLs, such as http://www.mydomain.com:70. Another drawback of this technique is that it violates the security best practices as your firewall will be required to allow all the incoming traffics for all the ports that are used by your server. To implement this technique, assign an unique port number to each site in the Web Site Properties dialog.
2) Another technique is to use multiple IP addresses with different sites running on the default port. Firstly, you will need to configure your server with multiple IP addresses in Network Connection properties. Then, assign an unique IP address to each site in the Web Site Properties dialog. Managing of multiple addresses allocation for the server requires additional administrative task. The more IP addresses the server is allocated, the larger is the attack surface, thus, it is not recommended (by me 
). Furthermore, if you are using public IP addresses, you will have to waste additional IP addresses for the server.
3) The last one is my favorite as we can use a single IP address and yet all the sites running with the default TCP port 80. All we need is to configure an unique host header for each site. Click "Advanced..." button on Web Site Properties dialog to configure host header for each site. You will just need to register multiple host records in the DNS server to map all the host names to the same IP address. But using this technique will have an issue using Integrated Windows Authentication on the web site due to Windows Server 2003 Service Pack 1 enhancement. I have posted something on IIS Security Enhancement in Windows Server 2003 Service Pack 1 for your reference.
Try these out and see which one best fits your requirements!
Stay tuned for Part 2 on which I will be discussing the options to host multiple SSL sites on the same IIS server.