Ok, so here this goes -been kicking this around. If this has been discussed already, my apologies.
So, one of the requests I've seen come up from time to time is for the capacity for players to specialize in knowledge - having access to various local, geographic knowledge and then being able to sell it or leverage it to their advantage. On the surface, I think this is great, but also there are several problems. For one, knowledge in and of itself is hard to 'trade'; how do you demonstrate it's accuracy and how do you get paid. Also, what are the immediate and long term uses of knowledge for a player - is there a limit to it's usefulness. Finally, how do you reconcile a player's knowledge with their characters?
The solution I came up with so far is character centric, and is an expansion upon the Pathfinder skill set. For now, I'm calling this little subsystem the "Leads" system.
Per its name, the Leads system uses....leads, which I describe as a type of knowledge resource. Each character will be able to take skills in any of the knowledges known, plus perhaps one or two other to cover certain situations. These include (Arcana, planes, religion, the planes, nature, local, nobility, geography, dungeoneering, engineering, legal*, and warfare*). Like other skills, you have a score that is rolled against various challenges.
The difference is what happens after you succeed one of those tests. When you beat a knowledge test, you get a lead, a finite resource linked to that knowledge skill.
From here, the lead can then be spent (or 'traded') to receive various benefits. Before I go into those possible rewards, I first will mention some ideas on how you acquire leads.
I roughly sort knowledge tests into two categories: passive and active. Passive tests are pretty straightforward - as long as you are in a certain location or situation, you periodically roll your skill against a target DC for that test, and gain leads. For example, while you are within a settlement, you might roll one test an hour against knowledge local - depending on your skill over a four-hour session, you’ll gain between 0-4 leads. While in a dungeon, you’ll test against a dungeoneering test, etc, etc. In other cases, you might gain leads while you’re under a certain situation: after you cast X spells successfully, you test against arcana/religion. If you use X combat maneuvers while at war, you test against warfare. In this way, your character gains a slow but potentially constant resource, depending on their actions. ALSO: not sure of the implications, but you can also make the resource of leads degrade overtime - this could help mitigatge people who try to overspecialize in getting one type of resource by gimmicks or grinding.
The other capacity would be active, and would be linked to completing various tasks, fulfilling contracts, killing certain monsters, interacting with certain in game objects, or as part of certain rewards. These would likely be more reliable, but less often.
With these leads, characters can then exchange them for a variety of goods, services, or boons. For instance, a mage might spend several arcana leads to see the spell list of an opposing caster, a settlement citizen might expend nobility leads to learn additional details about the settlements current leader’s activities. Travelers might use geography leads to reduce the cost/time on fast travel or reduce penalties to bandits. Lawyers can use legal leads to add additional items to contracts (the idea of fine print traps on contracts is slightly amusing), and so on.
The result of such a system would be an expansion to the economy of the game in the diversity of resources, and create markets for activities that can be designed for or against that might otherwise be less lucrative. Perhaps you really want an explorer - now they can collect loads of geography and nature leads, and sell them to bandits planning raids, settlements interested in ambushes, merchants looking in lower travel times, and so on. Crafters can gain engineering leads that can reduce construction times on items, which could have a volatile market. Dungeon delvers could collect arcana leads to sell to mages looking for a battle advantage. Tavern rats could hoard local or nobility leads that can be used for discounts on services, access to otherwise locked buildings (alignment restriction), or location information on various characters (and bonuses on assassination). Generals could use warfare leads to increase the bonuses to their companies, gain strategic bonuses, reduce pvp windows temporarily, or increase damage to outposts.
Arcane
Tests: cast spells, kill arcane monsters, reward items, level up arcane skills
Rewards: build certain items, predict spell list, activate certain quests, gain rep with faction
Dungeoneering:
Tests: visit dungeons, kill underground monsters, gain treasure
Rewards: Improve healing outside settlements, improve healing in area, gain info on escalations, gain faction rep, activate certain quests.
Engineering:
Tests: find certain locations, build items, harvest materials
Rewards: reduce build times, increase harvest yields, gain faction rep
Geography
Tests: fast travel, visit important locations, travel
Rewards: increase OoC Running, Make maps (better fast travel), recover faster outside settlements, faction rep, activate quests
Legal
Tests: draw or fulfill contracts, enforce or follow laws
Rewards: reduce crime penalties, make better contracts, reduce criminal flags, faction rep
Local
Tests: visit PoI, Settlements, defend settlements, use services, vote
Rewards: tax/service discounts, use restricted building, locate individual in area, rep
Nature
Tests: visit locations, kill natural creatures, find certain treasure
Rewards: track individuals, forage for resources, plan ambushes, faction rep, new quests
Nobility
Tests: manage company/settlemets, make feuds, wars, alliances, visit foreign settlements.
Reward: Gain influence, development indexes, gain info on leaders, faction rep, gain quests
Planes
Tests: visit locations, fight monsters, use certain items
Rewards: craft items, use certain spells (teleporation/scrying), faction rep, activate quests
Religion
Tests: use shrines, fight monsters, die, use spells
Rewards: respawn bonuses, use certain spells (divination/healing), faction rep, quests
Warfare
Tests: raid settlements, repel invaders, guard missions
Rewards: reduce pvp windows, field larger armies, gain combat bonuses, rep, quests.