Compact and powerful, the $650 (without drives) Drobo Mini accommodates four 2.5-inch drives, and has a USB 3.0 port, too.
Components are readily accessible and snap into place easily; and BeyondRAID technology offers users single- or dual-drive redundancy.
Buffalo Technology MiniStation Thunderbolt HD-PATU3
Buffalo Technology's $240 MiniStation Thunderbolt HD-PATU3 packs 1TB of storage in a compact, portable chassis.
The HD-PATU3 is the first Thunderbolt drive to come configured with both USB 3.0 and Thunderbolt ports on board. Even better: Both of the needed cables are included in the package. However, the Thunderbolt version of this product is preformatted to work only with Macs.