How to in asp.net mvc to get $_SERVER["REQUEST_URI"] ?

Question

I have the following url in my web browser:

http://www.mysite.com/Form/Go#key=100

I want from my controller to get the value from key, so I want to get this '100'. How can I accomplish this. I have Windows server 2008 with IIS7. The only way I found on google is to get

Request.ServerVariables["REQUEST_URI"]

like in php:

$_SERVER["REQUEST_URI"]

but I discovered that IIS7 does not contain it :(. I found some information that I should install FastCGI and the things will be ok, it was untill now the problem with some php applications such as Drupal. I made it all and the result is the same.

I woder that nobody hadn't the need to do such things until now, I serachd a good part of the time to find the solution, and 0. If someone has any idea please share it. Thank you.