In his USB Usability Q&A article, Scott Morris states that ISR routers (1800, 2800, 3800) use USB port for security keys. While that's definitely true, the usability of the USB ports go way beyond that. Once you insert a USB token into the port (and IOS release 12.4 recognizes tokens up to at least 1GB), you get a generic storage device (usbflash0: and/or usbflash1:) that can be used to:
Ivan Pepelnjak, CCIE#1354, is the chief technology advisor for NIL Data Communications. He has been designing and implementing large-scale data communications networks as well as teaching and writing books about advanced technologies since 1990. See his full profile, contact him or follow @ioshints on Twitter.