title: Best way to generate a machine fingerprint?
body: <p>I need to generate a unique string that will differ from machine to machine -- a "device fingerprint".</p>
  
  <p>What are...</p>
  
  <ul>
  <li>possible approaches for custom implementations?  (I've got a few ideas, but I figure you guys probably have BETTER ones)</li>
  <li>existing solutions?  (both commercial / non commercial are acceptable)</li>
  </ul>