Somewhat related, and a bit historical:

Back in the days of old (35+ years ago) United used to openly advertise in their timetables and flight schedules 'men only' flights, primarily using their French-built Caravelle jets. Most of their flights were between business centers (i.e. JFK-ORD). Today, this practice wouldn't even be tolerated (and I believe it is also illegal, since it violates the Civil Rights Act).