There are a few common ways to go about adding network-attached storage to your home infrastructure. You can buy a pre-populated NAS device (or home server unit) and plug it into your existing networking setup. You can pick up some kind of enclosure, fill it with hard drives, and plug that into your network. You can even go the extreme route and transform one of your desktop machines into a storage server through the use of existing open-source operating environments.
If you already have an existing external device, like a desktop-based storage device or portable hard drive, you've typically been out of luck. Accessing the storage capacity of these devices via your network would require you to plug said product into an existing PC or USB-friendly NAS device--not a helpful solution for a budget-minded individual that just wants network storage without a large cost or conversion.
Hitachi has simplified the networking equation by developing a device that bridges your USB-based storage with your existing network. It's called SimpleNet, and it works exactly like that brief description. On one end of the power-brick-shaped device are two USB connections, and on the other end sits a single 10/100 Ethernet port. Attach that side of the device to your network and you can hotswap any number of USB-based storage devices (be they hard drives or flash-based) to the two connectors on the other side.
While the fast Ethernet interface isn't the best news to Gigabit Ethernet aficionados, and the $80 price tag for SimpleNet seems a wee high at first, the device still looks to be a very convenient way to blend all of your untouched portable storage into a network environment. Depending on your storage needs and existing inventory, you might even save money versus a pre-populated NAS device or do-it-yourself build.