This could have been done a couple of ways, but here's how I did it:

...and here's the script that made it:

Keep in mind though, this page has to be on a server to work. If the page is on the hard drive, then there's no "location.host".

Let's say you wanted to create a link that returns the person one page before this one. Same format, just use the "document.referrer" statement. Are you starting to see the use of these things? Good.