If someone were to ask me which class I considered the most underwhelming in the Pathfinder Role Playing Game I would answer with the ranger. I don't say this because I think the class is weak from a mechanical perspective or even a flavor perspective, but because outside of the favored enemy ability there is rarely a chance for it to shine when compared to other classes. While I could go on at length about this (and probably will in another article) I think a better use of this space at the moment is to look at ways to expand the use of the favored enemy ability beyond a bonus to combat and the occasional survival role.
The idea behind the favored enemy class ability is that it represents the ranger spending a great deal of their time learning about a particular type of creature. While giving the ranger a combat bonus against said creature makes perfect sense, I have always felt the ability could be applied to a lot more situations. For this reason I have thought up ten ways to use the favored enemy ability that do not directly relate to combat.
1: Get a General Idea of the Design of a Lair
Part of a Ranger learning about a favored enemy is going to include learning about their habitat and this knowledge can be used in a number of ways. While it shouldn't give the ranger a map of the lair it can be used to give the ranger a general idea of how the lair will be used to serve as a base for a creature. This can include information on what kind of traps may be found, where those traps might be placed and more. If a player wishes to use their characters favored ability for this purpose have them make a survival check with the DC being determined by how detailed the information they are trying to get is.
2: Use in Diplomacy and Communication
Just because the ability is termed favored enemy doesn't mean the ranger can't or shouldn't use the knowledge of the enemy for diplomatic purposes. Because the ranger has spent a great deal of time studying the nature of a particular creature it makes sense that the ranger would be able to use this ability as an effective tool for communication and diplomacy. Using the favored enemy ability as a bonus to a diplomacy check could come in quite handy in several situations.
3: Understanding Physiology
The combat bonus against the favored enemy already assumes the ranger understands how to fight and enemy more effectively but it can also be used to justify an understanding of a creatures physiology. For example a ranger may know that a particular herb is known to make a beholder sick (bonus to herbalism/alchemy checks) or that orc's don't see the color yellow (bonus to hide checks). Using the favored enemy ability in this way allows for a lot of creativity.
4: Understanding Sociology
At first it may not seem like understanding sociology would be much of a benefit. However, when you consider that sociology is about understand the social structures of social creatures and that those social structures influence how a collective group will act or react in a certain situation the synergy of this knowledge with the favored enemy ability becomes easy to see. For example a ranger wanting to predict where a nomadic band of trolls might decide to spend the winter could use their knowledge of the trolls sociology to determine such information.
5: Understanding Religion
Religion is a huge motivator for a lot of creatures and there is no reason why a ranger can't use their specialized knowledge to understand their favored enemy's religion. This knowledge can be used in a number of ways from predicting times when a particular enemy might be engaged in some kind of religious right to understanding the motivations behind the latest drow incursion against a surface village.
6: Predicting Behavior
One of the reasons the favored enemy ability gives rangers a combat bonus is because the ranger knows the enemy well enough to predict their combat reactions. This knowledge comes from understanding the behavior of a creature and can easily be expanded to behavior beyond the realm of combat. While this bonus is applied to tracking attempts it can also be applied to other things such as knowing what time of night gnolls wake up or what kind of prey a particular predator will favor. When a ranger uses their knowledge to predict the behavior of an enemy there are many ways this can be applied outside of combat.
7: Educating Others
One of the best parts about having knowledge is passing it on to other people. When it comes to the ranger's favored enemy ability it isn't a very far jump to see how this knowledge can be used to help other people gain the benefits of the rangers knowledge. A ranger can educate a village about the nearby band of goblins and give the villagers a better chance of defending themselves against an attack or the ranger could give the rest of the party information about a vital part of a creatures anatomy.
8: Misdirection and Trickery
Because of how well a ranger knows their enemy it should be fairly easy for a ranger to use that knowledge to trick an enemy. A great example of this would be using a red herring to confuse a pack of wolves who are stalking the ranger. Another example would be the ranger being able to disguise themselves as a orc and infiltrate a goblinoid lair by drawing on the knowledge of what the goblins expect an orc to look and act.
The above are far from the only ways the favored enemy ability can be used beyond combat and each group will probably need to fiddle with different ways of making these concepts work. However, with a little creativity and experimentation it should be fairly easy to use the above concepts to make the ranger a little more interesting of a class to play.