The following c# application will return all of the MimeMaps defined in an IIS instance. The MimeMaps hold the mime types that IIS uses to return the ContentType header.

An example of such a header is application/octetstream

This example requires a reference to the Active DS IIS Namespace Provider in Visual Studio .NET. This reference enables you to use the IISOle namespace to access the IISMimeType class.

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections.Specialized;
using System.DirectoryServices;
using System.Collections;
namespace IISMIMEType
{
    class Program
    {
        static void Main(string[] args)
        {
            // Maintain a sorted list to contain the MIME Types
            SortedList sl = new SortedList();
            Console.WriteLine("IIS Mime Map - c#");
            Console.WriteLine();
            // Serve to connect to...
            string ServerName = "LocalHost";
            // Define the path to the metabase
            string MetabasePath = "IIS://" + ServerName + "/MimeMap";
            // Note: This could also be something like
            // string MetabasePath = "IIS://" + ServerName + "/w3svc/1/root";
            try
            {
                // Talk to the IIS Metabase to read the MimeMap Metabase key
                DirectoryEntry MimeMap = new DirectoryEntry(MetabasePath);
                // Get the Mime Types as a collection
                PropertyValueCollection pvc = MimeMap.Properties["MimeMap"];
                // Add each Mime Type so we can display it sorted later
                foreach (object Value in pvc)
                {
                    // Convert to an IISOle.MimeMap - Requires a connection to IISOle
                    // IISOle can be added to the references section in VS.NET by selecting
                    // Add Reference, selecting the COM Tab, and then finding the 
                    // Active DS Namespace provider
                    IISOle.MimeMap mimetypeObj = (IISOle.MimeMap)Value;
                    // Add the mime extension and type to our sorted list.
                    sl.Add(mimetypeObj.Extension, mimetypeObj.MimeType);
                }
                // Render the sorted MIME entries
                if (sl.Count == 0)
                    Console.WriteLine("No MimeMap entries are defined at {0}!", MetabasePath);
                else
                    foreach (string Key in sl.Keys)
                        Console.WriteLine("{0} : {1}", Key.PadRight(20), sl[Key]);
            }
            catch (Exception ex)
            {
                if ("HRESULT 0x80005006" == ex.Message)
                    Console.WriteLine(" Property MimeMap does not exist at {0}", MetabasePath);
                else
                    Console.WriteLine("An exception has occurred: \n{0}", ex.Message);
            }
        }
    }
}
    

Example Output

For more details on MimeMaps see:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/iissdk/html/b9b7a30c-5d24-4310-bb70-398c3129f6b3.asp

For more details on using System.DirectoryServices to configure IIS see:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/iissdk/html/d39fae66-abe7-4902-a3fc-f36151561f01.asp?frame=true