FreeNAS makes it easy to add storage to home networks
FreeNAS is a small, powerful, full-featured implementation of FreeBSD as a network-attached storage device. (It also happens to be January's Project of the Month at SourceForge.net.) If you're a Linux user like me, the BSD-speak used for devices and such might give you pause, but other than that small caveat, installation and usage shouldn't be a problem. It's powerful enough to be used in the enterprise, but it's friendly enough so that even a typical home office user can take advantage of it. Here's how I created an easy-to-use NAS device for rsync backups and FTP server on my LAN.
First, you'll need a machine to serve as a dedicated NAS box. An old PC will work just fine. All it really needs to have is an Ethernet connection, wired or wireless, and a disk drive. Even a USB key drive or CompactFlash card can be used for storage, but I went with a standard IDE drive. I used my test box to house FreeNAS for this review, and it was more than sufficient.