Given the amount of small portable devices nowadays, there are so many speakers hanging around. Audio processing algorithms, seemingly only for huge home theatre system, are definitely useful in this case.
Great overview. Regarding Bass boost (p.2), I used to believe that psychoacoustics-based bass enhancers needed at least two harmonics generated, the second and the third, in order to be any effective. Is just a frequency-doubling in the low-Hz region "good enough"? I guess myself that the answer depends on the application... like hearing aids or cell phones versus portable media players, etc.