If you're planning to upgrade the SSD in your Macbook Air, here's a neat little idea from Other World Computing: stick the old drive in a tapered aluminium case to provide an external drive which matches your laptop.
OWC offers the Aurora Envoy enclosure kit for $US20 when you buy any of their Mercury Aura Pro Express SSDs. The enclosure, which weighs 42.5 grams empty, is made of aluminium and has the same taper as the Macbook Air. The drives come in two speeds, with the 3GB/s drives suiting the 2010 Air and the faster 6GB/s drives only working with with 2011 Airs. Prices are so-so: $US248 for 180GB of 3GB/s storage, say, or $US780 for a 6GB/s 480GB drive (there are plenty of other options in between, of course). You can also buy the enclosure kit alone for $US48. [OWC via Engadget]