hahaha in the bottom are six hot swappable drive mounts. Very convenient and the hotswap bays are isolated from the case with rubber grommets so the vibration doesn't permeate through the case.
In the pictures I have an OCZ SSD (inside an Icy Dock 2.5" to 3.5" adapter) and a 2TB Samsung fitted on the right side and a single 320GB Western Digital on the left. I just use that for backups and unplug it usually. It's nice not having to fiddle with wires when plugging drives in and out.