wet filters, dispersion

so i'm interested in getting traditional subtractive synthesis sounds out of
max, and i've got a whole CV scheme biult with virtual 'modules' and such.

I'd like to make some filters that sound a little better/more interesting
than the stock svf, biquad, etc. I looked into the mcgill nord modular
online book, and they suggested that 'dispersion' was one thing that would
help to get 'wet' sounding filters.
http://www.cim.mcgill.ca/~clark/nordmodularbook/nm_filters.html#wet

I've tried doing some crossovers and doing my dispersion that way, but what
i'd like to try is to get some kind of dsp object that had a very non-linear
phase response but a fairly linear amplitude response, and put that inside
an explicit feedback path to the svf~ doing the actual filering.

Any info on making dispersion and/or improving the stock filters?

the desired finished product here would be an filter abstraction that would
respond to frequency and Q input, and maybe some third 'analog feel'
parameter.

thanks,
George