reFuse Software is developing the Lowender (Mac; $39) plug-in. This subharmonic synthesizer, reminiscent of classic analog dual band bass enhancer circuits, attempts to recreate the sound of a boom box.
The Lowender uses analog modeling and offers switchable frequency ranges so that the low end frequencies generated can be selected to fit the program material. In addition to the "classic" frequency range (generating subharmonics from 24-56 Hz), there are also ranges suitable for the lowest octaves of guitar and bass. The plug-in also has gate, drive, and output filter controls to help clean up unwanted bass rumble and even out dynamics.
The Lowender will be released in December 2006, using Cycling '74's Pluggo standard, which allows a single plug-in to interface with VST, RTAS, and AU.