For anyone who might not know there's also a pretty nifty device that joins the wifi network of your mac (or an ad hoc network between mac and wfi) and has a card reader so, you just have that in your bag and you don't even need to connect it to the air. Pretty damn sexy stuff. It was suggested for an ipad extra storage device also.
I can't find the link now, anyone who knows what I am talking about might chime in, it's a google search away anyway, just can't be bothered to do it.