The only bass I know of that has out of phase humbuckers is the old Gibson Ripper. One of it's settings was "out of phase-series". It was touted as a setting that could be used for funk. Having heard it I am pretty sure I'd never use it. It's not horrible...it's just super nasal. Interestingly, that bass and it's pups were designed by Bill Lawrence.

My G&L has been modded so that I can get pretty much any combination of in-phase coils. Out of all of the sounds I can get with it, I find that I use just two most of the time (neither of them a factory setting, BTW). Sometimes I like the neck pickup in single coil mode all by its self. Most of the time I like the neck pickup in single coil mode, and the bridge pickup in series. I never used the parallel settings. I think the only time I would is if I really wanted the single coil sound with the neck pickup solo'd, but needed humbucking to get the buzz out. Parallel generally seems like similar but not quite as good SC for the highs.

Of course the pups are in a different place on the bass I am working on... basically mid and neck rather than mid and bridge