R help - Aug 2005 - visualizing/summarizing a large, sparse logistic regression

I have data on ~340000 cases where it is desired to predict
binary outcome, Withdrawn, using up to 8, A:H, predictors in
a 3 x 2^7 design, but where the frequencies in these 168
cells vary enormously (1--108000).  As well, there are
two additional variables, Agency and Office, and it is
desired, among other things, to determine if the rates
vary with Agency and Office controlling for A - H.

I fit an initial model
   Withdrawn ~ A + B + C + D + E + F + G + H

giving all main effects significant, and am trying to find
a compact way to summarize and visualize the fitted rates
under this model, or a more complex model involving
Agency and Office plus potential interactions among A-H.

Can someone point me in some useful directions or to some
similar examples?

thanks,
-Michael

-- 
Michael Friendly     Email: friendly at yorku.ca
Professor, Psychology Dept.
York University      Voice: 416 736-5115 x66249 Fax: 416 736-5814
4700 Keele Street    http://www.math.yorku.ca/SCS/friendly.html
Toronto, ONT  M3J 1P3 CANADA