A great article from the news feeds.
The Western Digital PiDrive is available with either 314GB or 1TB storage capacity. The 314GB model is currently discounted by 31.4% and priced at $31.42. The drive comes bundled with the BerryBoot system installer that lets you install any of the operating systems stored on the PiDrive. At bootup, the BerryBoot menu lets you select which operating system you want to use on the Raspberry Pi. Note that while this $31.42 price is amazing, this price does not appear to include the necessary PiDrive USB cable or enclosure. If you are willing to spend $80, you can get the 1TB PiDrive with the same form factor in a kit that includes the drive, cable, enclosure, power adapter, and 4GB microSD card with SD card adapter.
Two cool things. The drive itself and the BerryBoot boot manager.
For people short on SD cards: Berryboot is a simple boot selection screen, allowing you to put multiple Linux distribution on a single SD card.
In addition, it allows you to put the operating system files on an external USB hard drive instead of on the SD card itself. Nifty