There's this brand, "Luna", or "Luna guitars". They make guitars and basses that are geared towards women.
If I didn't have a responsibility towards my homies, my streetcred and my, uhm, Long John Silver, I'd have one of these basses so fast. Sigh. Such are the trials and challenges of manhood.
they seem to be less about women and more about Artistry, Symbolism, Comfort and Playablility. Just glancing at their line up i'd say i know a few guys who'd buy some stuff, i'd have one of those Trinity Dreadknoughts if i could, if they made a acoustic Bass version of it I'd have to attempt to get it, but from an overview, definatly Unisex