Known for its popular cooling accessories, Scythe has announced its newest product which is meant to transform your unused 5.25-inch bay into a convenient 3.5-inch mounting bay.
Installation of the Scythe Easy Mobile Rack is as simple as installing an ordinary optical drive. The 3.5-inch rack is secured in an empty 5.25-inch drive bay using the included mounting screws, and is then connected to SATA power for Hot Plug support. 
Once installation of the rack is completed, users can insert any regular or slim 3.5-inch hard drive into the bay and close the hatch. Closing the hatch brings the hard drive backward for use, while opening the hatch brings the hard drive forward for replacement. Best of all, insertion and ejection of hard drives can be done without tools, without restarts and without data-loss.
The Scythe Easy Mobile Rack is available in Black only, making it blend well with the front of most darker cases. Check out the video below and the product page for more details.
Since a LOT of these kinds of things exist (just search on NewEgg for many examples), how about a comparison? Pros and Cons?
Rather than, "Hey, look at this nifty device!" how about, "Here are 5 single-bay devices for hot-plug, hot-swap 3.5" HDDs. We compare them for ease-of-use, durability, cooling, quality and value."
I'm working right now with a 3.5-in-5.25, two 5x3.5-in-3x5.25s, and a 4x2.5-in-5.25. The 3.5-in-5.25 is by far the simplest and also lowest-value. It would be great to see a review about one or more of the other form factors, because there are differences between the available devices on the market. Some of this might even be valuable over on the IT-Pro side of the publication.