i know its not eactly a component to the engine the same way a blower or a turbo would be but does it still fit under the catagory of forced induction since it works and does the same thing.
Nitrous is a power adder, but it is not forced air. Nitrous Oxide's main function is cooling the induced air and enriching the oxygen that goes into the engine. If you have colder and more oxygen rich air, you are able to burn more fuel and thus, make more power. The more NOS you use, the more fuel you have to use. Every good NOS system will have a way to put more fuel in the mix - in addition to what goes through the carb or injectors.
Yup, like Hawkco said... its not forced induction. Just like turbos, etc it requires more fuel to work right however.