LaCie Ethernet Disk mini ($170 [500GB], $210 [1TB]; ) This affordable NAS drive offers AFP, simple setup, mass storage, media server functionality, remote access, backup software, and storage expansion through USB. (; .)

NewerTech MiniStack NAS ($138 [160GB], $280 [750GB]; ) Sporting a Mac mini look, this portable 7,200-rpm NAS drive offers AFP, easy setup, ProSoft backup software, Time Machine compatibility, a security slot, and media server functionality. (.)

Netgear ReadyNAS Duo ($400 [500GB], $680 [1TB]; ) It's pricey, but this NAS drive features an extra drive bay to install an optional hard disk for mirroring data and offers AFP, remote access, media server functionality, and a BitTorrent client. (; .)

AirPort Extreme and Time Capsule

If you've got a wireless network anchored by an Apple ( Macworld rated 4.5 out of 5 mice ), you can connect just about any USB 2.0 external desktop hard drive to the base station for storage and file sharing. All Macs and PCs on your AirPort network will see the connected drive as an AirPort Disk, for which you can use AirPort software to set up account access, password protection, and read/write file permissions. If your network includes Macs and PCs, you'll need to format your drive as FAT32 so the PCs can use the drive.