It turns out that if you take an Ultrabook-style 7mm hard drive and put it in a sleek enclosure, you end up with a portable HDD that's barely any bigger, thicker or heavier than a smartphone. Toshiba guessed this might happen, and so it came up with a new addition to its Canvio range: the Canvio Slim, which sports 500GB of PC- and Mac-compatible luggage room, uses a single USB 3.0 connection for data and power, and is encased in either "graphite-black" or silver brushed aluminum. Look for it in stores from October priced around $115, including a three-