Feel free to prove me wrong if you have more HDDs. Post a pic of yours in the comments. :D
This is *primarly* the reason for getting rid of the Shuttle I had and getting a normal ATX case. All of these, except the bottom one, were in USB caddies and making a huge mess. :P
Not pictured: other HDDs in my house, including, but not limited to: 250GB (my laptop), 320GB (my backup drive), 320GB (dad's backup drive), 100GB (old USB HDD), 60GB (PlayStation 3), 320GB (my Sky+HD box), 500GB (downstairs Sky+HD box), 30GB (dad's old laptop, lol), 60GB (dad's laptop), and 250GB (old DVD recorder).