Just how thin is it? The GoFlex Slim measures 4.91- x 3.07- x 0.35-inches and weighs only 0.4 pounds. Sure, it only holds 320GB of space, but it does also come with USB 3.0 connectivity. That, combined with the 7200RPM drive inside, means transfer speeds that are 10x faster than a 5400 RPM with a USB 2.0 port. Naturally, the GoFlex Slim is backwards compatible with USB 2.0.
Ready to ship immediately, the GoFlex Slim retails for $99.99. For a 320GB portable HDD, that's a steep price. But it doesn't get much slimmer than this for that much space, so it's up to you to decide what's more important for you: more space on your external HDD or more space on your desk.