Modern homes are becoming just as much a maze of different networks as most small businesses. Add to that the fact that many small businesses are actually run out of homes or that employees of large companies also have an office in their home that must connect to their corporate network and you soon see that many home owners really need their own IT department.
Networks are not just for business purposes either. What about entertainment? Whether it's Internet, cable or satellite television it's a major piece of your home. Homes today now have multiple computers and/or gaming systems in them. Yes, these all can be networked together. Whether you just share an Internet connection or want to play the latest multiplayer game with multiple systems you'll need a network to handle it.
Today it is even possible to watch TV on your PC, or pull files off of your PC to view them on your TV. With the convience of todays DVRs you not only can watch your favorite shows whenever you want, but in whatever room you want no matter where you recorded it.
We have not even mentioned the well known but not normally thought of pieces that are really little networks themselves like phones, whole-house sound systems, and alarm systems.