This add-on for IIS (Internet Information Services) is invaluable for me, and I'm sure it will prove very useful for fellow web developers!
Before I knew about this, if I had to build a secure area of a site (https://) I would setup a new website in IIS with a slightly different name so I could test that my site enters and leaves the secure area properly. This way was ok, but certainly not ideal... especially if sessions where involved as the new "domain" would lose the session. So I done a search on this and found an official Microsoft add-on for IIS called SelfSSL, it's bundled with the IIS 6.0 Resource Kit!
Firstly, download the IIS 6.0 Resource Kit Tools from the Microsoft website. Then run the iis60rkt.exe from your server and follow the installation instructions. As SelfSSL if part of the Resource Kit bundle it will ask you want items you want to install, I personally selected the SelfSSL tool only, but feel free to select what you want, but you will not need any of the other tools to allow SelfSSL to run.
Once this is installed, you should be ready to apply the "SSL Certificate" to your development site(s). To do this:
Note: The /T is important, without this you may be prompted to accept the SSL certificate everytime you go to the secure area of this site in each new session.
Now when you go to https://<domain> you should see the page you want to see. You may be asked to accept the certificate the first time, make sure you accept this and you should be fine.