2.5 inch laptop hard drives
Most Mini-ITX cases require the use of a 2.5 inch hard drive, the size typically used in modern laptops. The one acception is the Cubic 2699 which is the only Mini-ITX case we know of with room for a full size hard drive.
Anyway, little cases take little equipment and these 2.5 inch drives are exactly what's needed if you are planning to use a little case or your own compact design.
Mini ITX Systems
Bootable USB Pen Drive
DSL on a CD