There are standards for AC mains power plugs and recepacles, too.
It's often said that the nice thing about standards is that there are so many of them. There are standards for all kinds of things, including, as I've come to find out, AC power connectors. The two heavy hitters in this arena are the National Electrical Manufacturers Association (NEMA) and the International Electrotechnical Commission (IEC).
Here are some of the most commonly used AC power connectors in North America:
NEMA 5-15-P: This type of plug is commonly referred to as a three-prong plug. The connector has two flat parallel blades with a round ground pin located between and above them. The female mating outlet for the 5-15-P is called a 5-15-R (R for "receptacle").
NEMA 1-15-P: This is a two-prong plug. Like the NEMA 5-15-P, it fits into a standard 110 VAC wall outlet, but it has no ground pin. The female mating outlet is called a 1-15-R, and most current versions of this plug have one blade slightly wider than the other.
IEC 320 C13/C14: Officially, this standard is named IEC 60320, but it is usually shortened to just 320. The C13 is a line socket and is very common in the PC world. The mating connector is the C14 plug. It is often mounted into a recessed panel or chassis on computer power supplies.
IEC 320 C5: This connector is a polarized power socket often found on the power supplies for notebook computers. The C5 connector has three round prongs arranged in a triangle, so that they look like Mickey Mouse ears.
IEC 320 C7: This two-prong connector is commonly used for connecting consumer electronics devices to the AC line. It is available in both a nonpolarized version and a polarized version. In the polarized version, one prong has a square shape, and the plug can only be inserted one way into the socket. Both prongs have a round shape in the nonpolarized version.
This short article just scratches the surface of power connector standards. IEC 60320, for example, also specifies connectors for uses of up to 250V. The NEMA specifies connectors for higher-voltage service, as well as connectors for three-phase power.