Only weeks after announcing a hard drive with a transparent lid, Western Digital has come up with something equally unexpected – an external backup drive that is actually mildly interesting.

The granite and black My Book comes in two versions, one for consumers and one that might better suit small business or power users.

The basic USB 2.0 version, My Book Essential Edition, has a number of features unusual in this class of device such as the ability to power itself on and off with the computer it is attached to, power management, and Google software to manage the drive’s contents.

The higher-specced drive My Book Premium Edition adds to this list dual Firewire 400 interfaces for drive daisy-chaining and improved performance, an external capacity gauge, and a comprehensive Western Digital-branded backup suite. The software is said to stop the drive being powered down while data is being written to the unit.

The oddest feature is the cooling design visible on the rear of the drive. As well as being passive for reduced noise, the vents are laid out in an elaborate pattern (click on 3D view) that turns out to be a message hidden in Morse code.

What this has to do with something as mundane as backup is anyone’s guess, but it is likely to appeal to people who like their technology to be “designed”. Either way, it should be pretty cool – that’s thermally and aesthetically.

"The My Book family is the next generation in external storage," said Western Digital’s Jim Welsh. “Consumers of digital media today are a much broader set of the population than in the past, and they want external storage that is easy to use and has an appealing design.”

Both versions are based on high-performance 7,200 rpm drives ranging in capacity from 160GB to 500GB, and are enclosed on what is described as a shock-resistant shell.

A 320GB version of the consumer edition is available for $249.95, while another hundred dollars on top of that will buy the more featured version in a 500Gb capacity. UK pricing should be announced next week in time for the European launch.