Run multiple sites from one IP in IIS

host headers are your friend

This link might help you.

http://technet.microsoft.com/en-us/library/cc753195(v=ws.10).aspx

You basically are going to run your sites on different ports and the tell IIS that http:// url1 maps to the site on port 80 and http:// url2 maps to port 81

You can use the same port 80 for all the sites. It's all about the bindings. You need to bind each site to a different host name:

www.domain.example
site2.domain.example
www.anotherdomain.example

etc.

You can do this by specifying the binding when creating a site. Then make sure you have configured DNS records to point at the same IP.

You can also setup a catchall DNS entry for a domain and point it at the IP of the server, then every time you create a site you can simply pick a new subdomain name at it will work straight away.