Yes, a Flash equalizer. We all heard it mentioned before…for some reason the word equalizer has been adopted to mean spectral analyser when mentioned along with Flash.
An equalizer will process the sound boosting or attenuating frequencies while a spectral analyser will only show you the spectral content of the audio.
Now with the new functionality of Flash Player 10 I hope this means that people will call things by their correct name since we now will have applications with both analysers and equalizers.
So with that off my chest, here is the code for an actual equalizer.
The algorithm is taken from this c++ snippet on musicdsp.org and might not be the highest fidelity but should be fairly efficient.
You can also view this online example. (requires Flash Player 10)