Taiwanese company Akasa announced the HDM-23 multi-utility 5.25-inch drive enclosure. This enclosure occupies a 5.25-inch drive bay in your case, and converts it an exposed 3.5-inch bay, or a discrete 2.5-inch bay for SSDs. The exposed 3.5-inch bay can then be used for devices such as fan-controllers in the 3.5-inch form-factor, card readers, such as the one pictured below (not included), or ye olde floppy disk drives. The 3.5-inch bay has mounting holes at the right spots to hold drives in the 2.5-inch form-factor, such as most of today's SSDs. Lastly, there are mount holes on its underside, to which you can attach a 140 mm fan. The enclosure measures 149 x 154 x 42 mm (WxDxH), about as big as an optical drive. It is priced at 880 JPY or about US $11. It will reach stores in late January, 2012.