A card reader is typically used to get data from the card onto a PC. I use a CF card in my digital camera, then plug it into a card reader attached via USB to my PC to download them for processing and sharing. I can read the card, look at the images just fine on the camera itself, but need to get them off the camera/card so I can share them. Yes, I could use a USB connection right to the camera, but a card reader is much faster and easier.
Class 6 micro SD cards are at least being advertised/sold - I have no experience with them -
http://www.newegg.com/Product/Produc...82E16820211380