Thinking more about the skill list and associated feats, consolidating rules again:
A PC gets 1+Int bonus languages and 1+Int bonus free Craft, Knowledge, or Profession skills in addition to their class skills. Unlike class skills, these three skills do not get a +3 bonus; their rank is simply the PC's character level. These skills are important, however, because they can add a +2 synergy bonus to the player's skill rolls whenever they're doing something closely related to their background as defined by these skills.
A PC also gets from 2 to 6 "adventuring skills" chosen from the following list, according to their class. A PC may choose any skill from the list, but if they choose one of the skills favored by their class they get a +3 bonus to that skill.
Fighters, Clerics, and Wizards get 2 skills.
Barbarians, Druids, Monks, Paladins, and Sorcerers get 3 skills.
Rangers and Bards get 4 skills.
Rogues get 6 skills.
Humans get an additional skill. Anyone may choose an additional skill from the list by expending a feat.
With the DM's approval, a player may pick out two applications of broad skills in lieu of a single adventuring skill. For example, a rogue who only has one skill left to pick and can't decide between acrobatics and athletics could designate Jump and Tumble as two skill applications equivalent to a single, more general skill. The rogue will be treated as having (level + 3) ranks when jumping and tumbling, but is considered untrained (no ranks at all) for balancing, escaping bonds, climbing, and swimming.
*Acrobatics (Balance, Escape Artist, Tumble): DEX, class skill for Bard, Fighter, Monk, Ranger, Rogue
*Acting (Bluff, Disguise, some kinds of performance): CHA, class skill for Bard, Rogue
*Athletics (Climb, Jump, Swim): STR, class skill for Barbarian, Druid, Fighter, Monk, Ranger, Rogue
*Awareness (Listen, Search, Spot): WIS, class skill for Barbarian, Bard, Monk, Ranger, Rogue
Craft: INT, class skill for no one
Handle Animals (+ Ride): CHA, class skill for Druid, Fighter, Paladin, Ranger
Heal: WIS, class skill for Clerics, Druids, Fighters, Monks, Paladins, Rangers
*Influence (Diplomacy, Intimidate): CHA, class skill for Bards, Clerics, Paladins, Rogues, Sorcerers
*Intuition (Sense Motive): WIS, class skill for Bards, Clerics, Paladins, Rogues
Knowledge: INT, all categories are class skills for Bards and Wizards. KS: Religion is a class skill for Clerics and Paladins.
Mechanics (Disable Device, Open Locks): DEX, class skill for Rogues
Profession: WIS, Musician is a class skill for Bards
Spellcraft (+ Knowledge: Arcana): INT, class skill for Bards, Druids, Clerics, Sorcerers, Wizards, and any other spellcasting
Spycraft (Decipher Script, Forgery): INT, class skill for Bards, Rogues, Wizards
*Stealth (Hide, Move Silently): DEX, class skill for Barbarians, Bards, Monks, Rangers, Rogues
*Streetwise (Gather Info, Knowledge: Local): CHA, class skill for Bards and Rogues
Survival (+ Intuit Direction, Knowledge: Nature): WIS, class skill for Barbarians, Druids, Rangers, Rogues.
Thievery (Sleight of Hand, Appraise): DEX, class skill for Rogues
Use Magic Device: CHA, class skill for Sorcerers
*Denotes a skill, or an application of a skill, that can be used untrained.
Craft, Knowledge, and Profession must be associated with a reasonably specific category, but may be taken multiple times. Here are some examples of some categories that PCs might be interested in. These three skills, and only these three skills, can grant a +2 synergy bonus to appropriate applications of the other skills, e.g. a PC with Craft: Locksmith gets +2 to their rolls to open locks.
Craft: Alchemy, Clockwork, Engineering, Herbalism, Locksmith, Shipwright, Smithing, Tailor, Trapmaking. This skill allows you to build and appraise items in your field of expertise, perhaps even recognizing magical items.
Knowledge: Geography (includes mysterious places), History (includes nobility and current affairs), Religion (includes undead and planar cosmology), Monster Lore, Natural Philosophy. You may also take Nature, Arcana, and Local as categories even though these are already subsumed under the adventuring skills listed above; doing so will grant a synergy bonus to the adventuring applications if you have taken those skills. Otherwise they grant you some theoretical, but not practical knowledge. (For example, a fighter with Knowledge: Nature might be able to recognize an edible plant if he saw it, but wouldn't be able able to make a skill roll to find enough of them to feed the party)..
Profession: Beggar, Courtier, Farmer, Fence, Guardsman, Merchant, Musician, Street Urchin, Sailor, Thief, Valet. The player can discuss with the GM beforehand what bonuses a given profession might provide. Guardsman might give +2 to Awareness rolls while the PC is on night watch, for example, and Sailor might give +2 to checks for keeping one's balance and using rope.
Some feats associated with the "adventuring skills"
Cross-training: pick one additional skill.
Skill focus: gives a +2 bonus to one skill (only once per skill)
Skill specialization: gives a +4 bonus to one specific application of an adventuring skill. Examples: running long jump (Athletics), spell research (Spellcraft), Bribery (Influence), ropewalking (Balance). The player is free to come up with their own ideas here, subject to DM approval. If the DM judges the application to be too general, they may allow it but reduce the bonus to +3.