title: Convert sequence of numbers to random-looking IDs?
body: <p>I'm working on an application where I need to generate unique, non-sequential IDs.  One of the constraints I have is that they must consist of 3 digits followed by 2 letters (only about 600k IDs).  Given my relatively small pool of IDs I was considering simply generating all possible IDs, shuffling them and putting them into a database.  Since, internally, I'll have a simple, sequential, ID to use, it'll be easy to pluck them out one at a time &amp; be sure I don't have any repeats.</p>
  
  <p>This doesn't feel like a very satisfying solution.  Does anyone out there have a more interesting method of generating unique IDs from a limited pool than this 'lottery' method?</p>