If you have a MacBook with few connectors like a MacBook Air, the Matrox DS1 is a very handy accessory. Not only does it provide more connectors, by just connecting a single Thunderbolt cable you've hooked up your Mac to a Full HD monitor, ethernet, speakers/headphones, and your peripheral USB devices. Especially the addition of USB 3.0 and a permanent ethernet connection is very valuable.
The Matrox DS1 is comes with either an HDMI or a DVI port. The highest supported resolution is Full HD, however. The Matrox DS1 is not a cheap accessory with an average price of $255, and that doesn't even include the pricy Thunderbolt cable that you will have to buy separately. If you can afford it, the DS1 is a very practical accessory for adding connectors hassle-free to your MacBook Air, and once you've made it part of your work environment, you probably don't want to live without it.