The New York Times' Personal Tech section features the 320-gigabyte eGo Helium USB 2.0 portable hard drive. The article says that MacBook Air owners will be drawn to this peripheral's design.
To quote from the article:
"The 2.5-inch eGo (compatible with Mac OS X 10.1.5 or above and Microsoft Windows 2000 Professional, XP and Vista) mirrors the Air’s aesthetics, from its own light weight (7 ounces) to its equally barely there frame (0.63 inches thick). The 320-gigabyte hard drive, which is available now and costs $150, comes formatted with Apple’s HFS+ file system and can store 1,280,000 photos and more than 5,920 hours of music."
I don't have the MacBook Air, but this peripheral is yummy nevertheless.