I love the ability to grab an old computer, fill it full of cheap hard drives, and install Freenas on a CF card or USB drive. Use built-in screen sharing to control.
For more technical information on this, see the Find Any File FAQ, What kind of disks do support 'fast search'? In particular, it supports Spotlight and fast file searches ( CatSearch), something that other NAS systems cannot do as well: They usually use a Linux system with netatalk and an ext3 file system which, compared to AFP with HFS, are not optimized for the ways a Mac can search. The advantages to using an actual Mac over a true NAS system: In my case, I had an old MacBook that wouldn't hold a charge anymore so I rigged up an eSATA connection to my 2TB external drive.
