Tom's Hardware had a look at WD's new WD1500AD Raptor-X hard disk. This is one of the fastest HDDs on the market and it's designed for case modders as it has a window that enables you to see your hard drive spinning.
The center top part of the Raptor-X is equipped with a coated transparent polycarbonate, which allows for an insight into the mechanical heart of the drive, particularly fascinating while the drive is busy. The website www.wdraptorx.com explains how this was realized, since the clear cover material has to be able to cope with changing inside pressure levels, temperature fluctuations and electrostatic discharge. You may have seen clear cover drives at exhibitions or shows, but the Raptor X is the first production drive that offers this feature to the masses.
You can check out their full evaluation over here. The only bad thing about this HDD is the extreme price. A $349 price tag for a 150GB HDD isn't really cheap, but you do get the fastest HDD on the market!