Well, a free plugin is always welcome.
Waves is doing a giveaway (well more like a contest) to get a free licence of MaxxBass, if you don’t have it (like I don’t) so maybe you can get it now
Some info from waves:
MaxxBass® uses psycho-acoustics to calculate precise harmonics that are related to the fundamental tones of sound. When these harmonics are combined, it creates the effect of lower, deeper frequencies. MaxxBass extends the perceived bass response by up to 1.5 octaves while preserving the dynamic range and character of the original bass
And of course the contest link shortenened : http://tinyurl.com/MaxxBass