Paladins? Rangers? Fighters have a thousand feats for a reason! :D

[aimlessPolymath]

My take on a Favored Enemy feat:

Hunter:
Requirements: Knowledge (any) 4 ranks (1 in pathfinder), Ranger, BAB + 3
Benefits: By spending 8 hours in a library containing sufficiently detailed information (one which can answer DC 20 questions on the subject), you gain the Favored Enemy ability, with a +2 bonus, against a type or subtype you choose.
Special: You can only have one bonus at a time through this ability. Acquiring another replaces the oldest benefit you have.



Somewhat related, one of my old projects: A feat to start to subsume Inquisitors into Rangers.

Tactician
Requirements: Favored Enemy (any) +2
Benefits: As a swift action, you may lose your Favored Enemy bonus to damage against any number of favored enemies, and exchange them for the following types of benefits:
-A bonus to attack rolls against the given class of creature. The bonus is equal to 1 + one-half your Favored Enemy bonus.
-A bonus to AC against attacks by the given class of creature. The bonus is equal to 1 + one-half your Favored Enemy bonus.
-A bonus to saving throws against the given class of creature. The bonus is equal to 1 + one-half your Favored Enemy bonus.
When you do, you can also alter or reverse any such decisions for other Favored Enemies you have.

On spellcasting... I'm reminded of those feats from Complete Arcane, the ones that give spell-like abilities.