No form of magic, more than divination, causes DMs distress and regret in their campaigns. Adventures designed without divination taken into account can be ruined with a single spell. Adventures designed with divination taken into account can be ruined by a PC's poor selection of spells. DMs can't win with this magic spell-type and in order to combat it's "logic." But, this isn't an easy problem to solve and we need to know how you play in order to address this.
For starters, figure out how your game world deals with magic. What's the percentage of people that would even have access to divination magic? Remember 90% of the population is peasant class. Of the remaining 10%, 10% of that is adventurers. Of that, 10% is wizards. Of that, 10% are divination masters. So. . . 10% of 10% of 10% is .1% of the population.
If your game world looks anything like this, chances are few people are concerned about wizards peeking into their bedrooms. Certainly a wizard may take a few detection or augury-type spells here and there, but very few are going to have detect thoughts, clairvoyance, or scrying. The general populace of your game just aren't going to be too concerned about wizards peeking around the corner.
Other wizards will, but your standard merchant will not.
If divination is rare, the game world won't bend to accomodate it. If divination is common, NPCs will live in fear of the police-state that reads your mind and watches what you're doing. Divination's power ebbs and wanes with the level of involvement it has in the lives of everyday people.
Something else to think about is that all divination spells can be replaced with a single die roll system for divination magic. Instead of spells per day, diviners get power points to fuel "detection" and "knowledge" spells (see page XX of magic for points per day). The more points put into the spell, the greater the bonus to the die roll. The die roll is a 1d20 + the caster's spell level + the point spent. A variable DC is selected based on the information the caster is trying to uncover. For instance:
If the PC wants to know where's a good place to eat in this town, the DC is probably only 10.
If the PC wants to know the name of the bartender before they enter the tavern, the DC is 15.
If the PC wants to know what the bartender is thinking when he walks in the door, the DC is 20.
If the PC wants to know which brewer made the ale they are about to drink, the DC is 25.
If the PC wants to know the absolutely perfect antidote to the poison he just drank, the DC is 30. If the PC wants to know the name of address of the person who made the poison, the DC is 35.
If the PC wants to know why the poisoner was hired to kill him, the DC is 40
If the PC wants to know the true name of the witch who hired the poisoner to kill them in the first place, the DC is 60.
Does this make sense?
That stated, DMs still don't want their entire adventure ruined with a casting of a single 3rd level spell. So, we can't ignore what exists now. The key to fixing the present spell system lies in making divination a little less predictable, but also a little more flexible.
For instance, the 0-level spells of detect magic and detect poison along with detect undead and detect secret doors, should be a single spell called detection and each time it is cast, you select from a list of things you are looking for.
Components: V, S, MF*
Casting Time: 1 action
Area: Cone-shaped enanation
Duration: Concentration, up to 1 min./level
Saving Throw: None
Spell Resistance: No
You can sense the presence of [chaos, evil, fire, good, law, magic, mineral, poison, secret doors, undead, water]. The amount of information... blah, blah. None of the information from the spell changes, with the exception that the information is accurate per the spell caster rolls mentioned in the previous post. And the DM rolls this secretly. Since divination magic is less reliable than any other magic type, the DM has absolute control over how the information is relayed. A very poor roll (19+) might indicate that the caster believes there is a secret door where their isn't one or that an evil presense is much more powerful than it actually is. For this reason, the DM should probably make the rolls in secret.
[Just like Listen and Spot checks should be made in secret.]
Divination spells (like detect snares and pits) that duplicate the ability of another class (Rogue's searching for traps) should be removed from the game. There are far too many of these (in all colleges) and I can't go into them all, but bear in mind that I will be addressing them as I go.
Moving to higher level spells, augury, contact other plane, and discern location are powerful divination spells that can either slow down a game or be far too abusive in scope. Augury's miss chance makes it fairly balanced, but contact other plane should be a 4th level spell with a greater miss chance and a gp cost. At this point, it merely becomes a useful tool for getting the PCs on track with the game. Like Bardic Lore (lame), this is a tool for the DM to get campaign information into the hands of the PCs in a less than heavy-handed way.
But then, spells that are used to "get on track" shouldn't count against the PCs spells per day, either.
On the other hand, foresight might possibly be the lamest 9th level spell ever created. Not only is the effect more in line with a 6th level spell, but the duration is so short, it's barely useful for two encounters. It's also a 5th level barbarian ability, but we'll ignore that for now. Foresight's placement as a 9th level spell indicates the designer's inability to concoct a pair of truly useful high-level spells for this school.
Divination spells are almost the COMMON SENSE advantage in GURPS. If you always do impulsive or stupid things with your character, take this ability to avoid doing something really dumb. Diviniation protects you from not asking the right questions during the "role-play" part of the adventure.
Material Components/Spell Focus
Anyone choosing to focus on divination as a college should be able to cast spells quicker, perhaps. Or, use material components faster. Or both.
Material components used in conjunction with a divination spell increase the spell casting time but increase the reliability of the spell. This is in line with true African divination magic which often took several hours to cast, special rocks, and an understands of what it was that one was trying to divine.
No other college more needs "specialized" and "flavor" material components than divination.
I don't have much more to add, I'm afraid. Divination really requires a whole new class built around its function. With the exception of detection spells, it really needs to be trimmed back extensively.
Below is my list of divinations spells. I recommend commenting if you see alterations that could be made to this class of spells.
0-LEVEL SORCERER/WIZARD SPELLS (CANTRIPS)
Detection: See above.
Message: If whispering wind is divination, so is message.
1ST-LEVEL SORCERER/WIZARD SPELLS
Comprehend Languages: You understand all spoken and written languages.
Identify: Determines properties of magic item.
True Strike: +20 on your next attack roll.
2ND-LEVEL SORCERER/WIZARD SPELLS
Detect Thoughts: Allows “listening” to surface thoughts.
Locate Object: Senses direction toward object (specific or type).
See Invisibility: Reveals invisible creatures or objects.
Whispering Wind: Sends a short message 1 mile/level.
3RD-LEVEL SORCERER/WIZARD SPELLS
Arcane Sight: Magical auras become visible to you.
Clairaudience/Clairvoyance: Hear or see at a distance for 1 min./level.
Detect Weakness: Gain an insight bonus against target creature equal to Wis+Int (or maybe level) modifier for 1 min./level. Requires a full round to cast.
Tongues: Speak any language.
4TH-LEVEL SORCERER/WIZARD SPELLS
Arcane Eye: Invisible floating eye moves 30 ft./round.
Contact Other Plane: Lets you ask question of extraplanar entity.
Detect Scrying: Alerts you of magical eavesdropping.
Locate Creature: Indicates direction to familiar creature.
Scrying: Spies on subject from a distance.
5TH-LEVEL SORCERER/WIZARD SPELLS
Prying Eyes: 1d4 +1/level floating eyes scout for you.
Telepathic Bond: Link lets allies communicate.
6TH-LEVEL SORCERER/WIZARD SPELLS
Analyze Dweomer: Reveals magical aspects of subject.
Foresight: “Sixth sense” warns of impending danger.
Legend Lore: Lets you learn tales about a person, place, or thing.
Moment of Prescience: You gain insight bonus on single attack roll, check, or save.
True Seeing: Lets you see all things as they really are.
7TH-LEVEL SORCERER/WIZARD SPELLS
Arcane Sight, Greater: As arcane sight, but also reveals magic effects on creatures and objects.
Scrying, Greater: As scrying, but faster and longer.
Vision: As legend lore, but quicker and strenuous.
8TH-LEVEL SORCERER/WIZARD SPELLS
Discern Location: Reveals exact location of creature or object.
Prying Eyes, Greater: As prying eyes, but eyes have true seeing.
9TH-LEVEL SORCERER/WIZARD SPELLS
Moment of Prescience, Greater: You gain insight bonus on single attack roll, check, or save. Free action to cast.
Truename: Spell reveals true name of "anything." Especially useful in a campaign where true names mean something.