Block access to subdirectory using Web.config

IIS 7 has a new "request filtering" feature. You probably want to use the hidden segments configuration:

<configuration>
 <system.webServer>
  <security>
   <requestFiltering>
    <hiddenSegments>
     <add segment="BIN"/>
    </hiddenSegments>
   </requestFiltering>
  </security>
 </system.webServer>
</configuration>

This causes http://yoursite/bin to not be servable (but http://yoursite/binary still works)

Check out: http://learn.iis.net/page.aspx/143/how-to-use-request-filtering