If you need your laptop to read to read an SD card but the laptop does not have a memory card slot what device can you buy to read the card?

You can buy an SD card reader which plugs into the USB port on your laptop. The card is read like an external memory device.

Here's an address for an example at "Tiger Direct":

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=6634192&CatId=2825