This is all interesting and usable, thanks.
 
 
 
 

Another free plugin:
 
http://www.alexhilton.net/A1AUDIO/index.php/a1stereocontrol
 
"Safe Bass

The integrated "Safe Bass" algorithm centers all bass frequencies
below a adjustable value right back into the middle of the stereo
field. This gives your tracks the solidity and definition you want
while preserving maximum transparency and sharpness. Similar
techniques were used by professional studio producers over ages
with either expansive hardware devices like elliptical equalizers or
even advanced m/s-processors. With my plugin you will be able
to manage this complicated task with a minimum effort.

Simply turn on "Safe Bass" and adjust the frequency if needed.
That's it  - It's really that simple ! (Especially for Mastering)
 
(PLEASE NOTE: THIS PLUGIN WORKS ONLY ON STEREO TRACKS !)"
 
Hope this helps.

Or this one, which is much simpler, if you prefer simple, but still free, and 64bit. 
http://www.gvst.co.uk/gmonobass.htm
 

Mid/Side processing would be my go-to here. It's possible to convert stereo to Mid/Side tracks, but there are indeed EQ's that do all the complicated work for you. The aforementioned plugins are all good choices, and we also have the Hoser XT available on our store that does M/S processing. Keep your eyes on the Cakewalk Blog -- more info about M/S processing coming soon :)