Many of today's audio/video receivers will have second zone capabilities in one way or another. The most common way is to use the Speakers A and Speakers B outputs. Speakers A is most commonly used for your Home Theater main front speakers and Speakers B is used for a second set of speakers somewhere else in the house. However, most receivers will not run both Speakers A and Speakers B at the same time, it is either/or.
Some 7.1 Home Theater receivers will actually have a powered Zone 2 output that will steal the output power from the 6th and 7th surround channels to power a second set of speakers. The best way to hook-up a second zone from one of these receivers though is to use the Zone 2 pre-amp output (if equiped). This out will integrate into a multi-channel amplifier to power multiple speakers throughout the rest of the house and incorporate volume controls to control the volume of each pair of speakers independently.
If your receiver does not have a Zone 2 pre-amp output then you will have to use the Speaker B output. But what if you want to power more than one additional pair of speakers? You will need a speaker selector box that will distribute the power among several pairs without harming the amplifier on the Speaker B output section.