Intuition (Wis)
Sometimes, you walk into a cave and just feel that it's cold and empty. Other times, you walk in and get a shiver down your spine. Your guide, whom you hired for their knowledge of the local lure, backs away and refuses to go any further. Even before you spot physical clues that support your fears, you know that something big and dangerous hides deeper in...
This is what the Intuition skill is for. I've played with DMs who've merely given this as a feat choice, offering a slight bid of roleplay to those who select the feat, and I know one DM who goes so far as to offer it as a Flaw choice, saying it's a character's irrational fear. But being someone who feels he's managed to train this sense, I think it's far more apt to be a skill, and hopefully, I'm about to prove it.
The Intuition skill can be used untrained, but it works as well as a modern person's ability to intuitively sense things (in other words, not too well). A character's wisdom score is their only modifier when used untrained, so characters who rely on reason aren't to incline to bother rolling it. An Intuition check's results are different from typical skills, as the DC is merely a high point goal, similar to a knowledge check. Comming up short doesn't just mean you failed, it just means your not as sure or you don't get all the possible info.
For an example, I'll give you a fairly resonable senario. Typically, there is just one roll for a room or situation, and there are no rerolls. You get what you get and you hope no one thinks your going crazy.
Situation: A party has just entered a stone and mortar room at the end of a natural cavern tunnel. The stone door at the other end of the room is exactly as the old scholar said it would be, highly decorative and laden with runes that shield the location from scrying magic. All that should be left is to open it and enter the lost temple, but the little halfling bard has rolled intuition.
DC Result
DC-5 Something just feels off about the door
DC-10 Something about the room isn't right
DC-15 Walking in the room gives you shivers
DC-25 The runes don't feel like they do what the scholar said they should do, You don't know what
the ancient runes mean, but they appear to you more like pictures of fire and explosions
and scary monsters. Anyone else might see them as just random lines making patterns.
If the halfing rolled and made the main DC, he may share the thought with the party, who may spellcraft the runes or otherwise research them before touching the door.
If the halfling rolls between a 24 and a 15 and shares his thoughts with the party, they MIGHT still feel inclined to roll some further investigative checks to determine their friends odd gut feelings.
If the halfling rolls between a 14 and a 10, the only one who may feel inclined to do any extra checking is the halfling himself, and only barely.
If the halfling rolls 9 or less, nothing feels wrong with the picture at all, at which point the halfling himself may just go try and open the door, summoning horrible monsters into the room while triggering a fire-y explosion in the doorway that leads to evil lich's now heavily warned underground lair of monsters and undead.
If the other party members choose to ignore the halflings warnings, the DM may even choose to let the halfling act in the surprise round the summoned monsters would get, or at least say the halfling is not flat-footed, and may keep his full AC during the surprise round.
A DM may also use this as his NEWBIE TRAINER skill. When I have new players in my group, I'll teach them the mechanics the best I can, but role-playing is all experience. Granting a new player a newbie bonus of +5 to this skill always seems to let them get used to things like searching a room for traps, spotting what's wrong with things that're too obvious, and (as only one of my players will get this joke) looking up as they enter a room. I can be kind of an excuse for the DM to grant subtle hints if, for example, it turns out the players are being more thick-headed then he suspected.
CLASS SKILLS:
This list will be hard to ever truly consider complete, but as a general rule, consider classes that really on their knowledge and the facts to be unlikely to call this a class skill. Those more in touch to their natural side or instincts, often those with divine magic, tend to have a strong intuition.
(I intend to continuously edit this list, so check before new campaigns for added books and classes)
Currently included books: Core books
Core Classes:
Bbn: C
Brd: C
Clr: C
Drd: C
Ftr: cc
Mnk: C
Pal: cc
Rgr: C
Rog: C
Sor: C
Wiz: cc
Prestige Classes:
DMG:
Arc Arc: C
Arc Trk: C
Archmge: cc
Assasin: C
Blkgard: cc
Drg Dcp: C
Duelist: cc
Drf Def: cc
Eld Knt: cc
Hiropnt: cc
Hzn Wlk: C
Loremst: cc
Mys Thr: cc
Red Wiz: cc
Shdwdnc: C
Thmtgst: cc