If you're in the market for mass storage, the Seagate GoFlex line offers the GoFlex Desk desktop drives with up to 4 TB for around $220, and the GoFlex Portable handheld drives with up to 1.5 TB for around $169 (see previous post). Both these lines also use the GoFlex adapter systems to support multiple data interfaces, beyond USB 3.0 / 2.0.
But if you're looking for even more portability, the Seagate GoFlex Slim Drive shrinks a fast 7200 RPM drive with a USB 3.0 interface down to roughly width of a pencil, with 320 GB of storage for around $70.
This puppy is not quite 3 x 5 inches, or about the size as a post-it pad -- but less thick. The USB 3.0 port fits on the end (the new port is smaller than a standard USB 2.0 port), and the end is removable with the GoFlex interface, which can plug into the Seagate FreeAgent GoFlex Net Media Sharing Device to make the storage on the portable USB drives available over your local network.
However -- If you're interested in more storage, be warned that monsoon flooding in Thailand has seriously impacted hard disk drive production for the major vendors, so plan ahead for shortages and/or price increases. See Tom Coughlin's update on the Forbes.com blog.
See my Portable Storage Gallery for more on portable drives, from USB keys to desktop drives.
And see my Holiday Gadgets 2011: Portable and Wireless feature for more on storage and other holiday goodies.
Find the Seagate GoFlex Slim Drive on Amazon.com