andy, in certain ways, the way mike has gone may be more to the point. (tho, i might do it with mixed p and j coils).
my pickup is made up of 6 coils (see the picture, it's small tho').
2 front p-bass
2 middle p-bass
2 back j-bass
the p-bass coils can be used in 5 different configurations: front 2, middle 2, split p, reverse split p and all 4 (vaguely musicman-ish). i control that with a 5-position rotary switch.
then there's a 3-position toggle that can be only p coils, only j coils or a combination of the j coils and p coils (variations decided by the rotary).
all complete passive.
i don't use the split p/reverse split sounds very much. not counting them, i can get 7 combinations of sounds that i thing are pretty different.
hopefully this makes sense.