title: Corporate login solution
body: <p>Imagine a situation where a large corporation wanting to give their users access to a website, without having to individually register each of their users with the target website.</p>
  
  <p>EDIT: Registrations to the website are paid subscriptions, so normally users would pay and get their accounts activated via support line (or it happens automatically). Corporate would want to purchase a bulk subscription, and add/remove the users under that, subject to a maximum limit, so the individual users don't have to go through the hassle.</p>
  
  <p>Users should still have their individual accounts with the website(instead of a single account used by all users) so that  they can have their preferences saved, etc.</p>
  
  <p>(Prefer a solution where most of the implementation happens in the website side)</p>
  
  <ol>
  <li><p>Are there any accepted patterns, solutions for this kind of scenarios?</p></li>
  <li><p>I thought of if we could use OAuth(Yes, I know it's authorization,
  but may be we can use it as an authentication tool as well, right?),
  or OpenID like protocol. But the corporation does not have such
  mechanism exposed to the outside. Are there any "off the shelf" kind
  of products which we could use to create a OAuth/OpenID
  implementation against an existing user base, lets say
  ActiveDirectory.</p></li>
  </ol>