The [Fares/GOL] Engine (which is currently in Beta) lists the ~40 lowest published Fares for the requested route (and carrier, if specified).
To retrieve the Fare Basis Code for a Fare you need to double-click the desired Fare Item(s).
That doesn't make it much more useful for easy access. You still have to click on every fare to find out what it is. As a bonus, since they're sorted by price and one cannot specify booking class anymore, different cabins are now mixed within the results, for example a Z fare is between a cheaper economy fare and a full Y fare. Very convenient.