While the writer probably can’t do a virtual SAN, they can definitely do a virtual NAS. I’ve been using the Belkin USB hub ($89 at CompUSA) for a few months now & I love it. It alllows for 5 USB devices to be attached and shared across the network. In my configuration i have two printers and three hard drives shared. The drives can attach to one computer at a time, but can be disconnected at will. Another tool used in my house is an SMC Storage Access Point ($50 on eBay). It acts as an access point for my wireless network & provides for three network-accessible storage devices (one internal & two USB).
There are a few open source software packages on the Internet – FreeNAS (www.freenas.org), OpenFiler (www.openfiler.com – open source, not free). Also, check out SourceForge for others.
I hope this helps,