How to handle complex redirection requirement? I have a content type defined with a field storing the URL for accessing an external web resource and am looking for a way to have my Drupal 7 instance manage the redirection to this external site based on the nid contained in the incoming request path (ie. mysite.com/resource/123 redirects to the location stored in field_data_field_url where nid = 123). 

The driver for this requirement is that our partner sites need to publish links to these resources that will not be subject to change. Drupal will house the database of resources and I am hoping to provide an endpoint that handles the redirect without further action from the user. 

I have begun exploring the Services module in attempting to solve this problem but am not making headway in figuring out how to ultimately perform a redirection. I would appreciate input on whether this is an appropriate case for this web service approach or should I be looking at another way to tackle this problem within the Drupal framework?
You could use Services, you dont have to.

1) To have remote resources you need to create a url in drupal to consume data sent to it (Services can indeed do this). eg, mysite.com/secret/submit-a-resource-location. You could make this in a custom module with hook_menu, it could store values in a table with NID, and RESOURCE_URL as the columns.

2) If you goto some path on your site like mysite.com/passthrough/NID you could look at the NID passed in and in the hook_menu page_callback function and use drupal_goto to go to your remote url.

Eg:

function mymodule_menu() {
  $items['secret/submit-a-resource-location'] = array ( /* ... */ );
  $items['passthrough/%'] = array( /* ... */ );
  return $items;
}

function mymodule_passthrough_page_content($arg) {
  $result = db_query("SELECT resource_url FROM {external_resources} er WHERE er.nid = :nid", array(':nid' =&gt; $arg))-&gt;fetchCol();
  drupal_goto($result['resource_url'], 302);
  // implicit exit here by drupal goto.
}