One of the greatest things about universal serial ports (USB) is that a single port can be connected to dozens of different devices at the same time. Using a simple hub, a user can extend their system’s technical capabilities to include a multitude of different devices including external storage drives, lava lamps, missile launchers, external sound cards, microphones, and headsets.
Yes, while some devices are silly (pet rock, anyone?) the principle behind USB is very solid. This is one of the reasons why USB 3.0 is expected to do so well, even against a much faster and more powerful Thunderbolt standard.