Obviously, the number of devices that you can attach to your PC is enormous, and attempting to write a chapter that covers all of them is next to impossible. However, with what you just learned about SCSI, USB, PCMCIA, and IEEE 1394, along with what you will learn about printers in Chapter 12, Ethernet interfaces, and so on, you should be well equipped to take on almost anything. For example, you know how to identify a USB scanner; it's just a matter of installing the appropriate drivers and software (the most popular Unix scanning system is called SANE, if you are interested).
This book isn't finished with devices just yet, though. In particular, Chapter 13 has information about tape drives, and Chapter 17 contains tips on how to purchase hardware so that you can avoid Linux compatibility nightmares.