Due to popular demand, I added identity delegation (aka ActAs) support to StarterSTS.

To give this feature a try, first download the new bits and add a enableActAs = true to startersts.config. You then have to configure which user account is allowed to delegate, as well as the target realm to delegate to. This is done in usermappings.config, e.g.:

<userMappings xmlns="http://www.thinktecture.com/configuration/usermappings">
    <user name="middletier">
      <mappings>
        <mapping type="ActAs"
                 value="https://server/service.svc" />
      </mappings>
    </user>
  </users>
</userMappings>

Please use the forum for any feedback. thanks!