The above post makes a good argument for the benefits of monopoly. The specific benefit of monopoly in the area of utilities is often recognized by local governments. Municipalities often grant monopoly rights to electric and water companies in a given area.
This once was the case in phone service as well, but as advances have been made in transfer technology (I'm not sure if that is exactly the right term...), monopolies in this particular utility are becoming less common. They still exist, but seem to be losing traction, as you might see in your own area if you can get phone, internet and cable service from various service providers.
Competition in the area of phone/internet/cable seems to be beneficial to consumers, driving down prices.