We have seen our fair share of devices that connect the various flash mediums (CompactFlash and SD being the most popular) to system drive ports such as SATA, IDE, or laptop IDE allowing you to use those card types as system disk drives. This isn’t much different, and whether you are doing it to free up a USB port, or because you want to install an OS on your 16GB SD card, its not too expensive for what it does.
Not all computers come with built in card readers and those that you build yourself likely lack them as they are kind of unattractive. So, you could run to your local brick and mortar store and pick up a card read for the specific card type you need read, or a multi-format card read, either one going for about $20+/-.
Or, you can pick up an adapter like this, that not only allows you to use it like a simple card reader, but should you ever choose to do so, you can install Linux or some other OS on it and use it as your OS drive. The benefits of which I hear are major, namely in the speed department, provided you have a fast enough card. The best part is, your computer will read this thing just like it were an IDE drive, no drivers needed, and, its shock resistant, lowers the head in your PC case, makes zero noise, and the read times are noticeably faster. If you want one, you can pick them up for $24.99 from gizfever.