Just thought I'd post a couple of links I found today that are useful.

http://www-staff.lboro.ac.uk/~huanr/A_Rimell_thesis.pdf

This is really cool and discusses things like magintude + phase response, driver dispersion, cabinet diffraction, frequency and time domain stuff, polar response abberations and equalization, directivity, psychoacoustic's of the human ears, time varying filters, parallax, multiple driver summation, lots on room interaction and analogue and digital crossovers, and more!

Also check out the main site http://www-staff.lboro.ac.uk/~huanr/ which has some other great articles too. A lot of it is on phase driver summation stuff (but not all) which I'm sure a lot of people are interested in (Mike just asked a few days ago this).

Adrian