Just a random thought that popped into my head. What if Specialist Wizards, based on their knowledge of their particular fields, were given more than just an extra spell slot per level? What if they also received tips on different matters over time?
I'd suggest a series of hidden spellcraft checks, which occur in some cases unprovoked, or can be activated, depending on your school specialization.
Divination - Detect the presence of magical wards. Higher rolls determine the number of magical wards, and exact spells with the highest rolls. This could work on both buffs and things like curses.
Evocation - Determine the elemental weaknesses of the chosen creature.
Transmutation - Possibility of gaining more or better shards when Sundering an object.
Conjuration - Determine if an item can be used as a conjurative reagent without needing Conjurative Sand.
Illusion - Determine the presence of any illusion magic in the area, must be actively used and DC is based on the STR of the illusion. (So the Shield is going to be impossible to detect for anyone short of an archmage, really.)
Enchantment - Re-roll a failed bluff/persuade/intimidate check.
Necromancy - A player tool that will guarantee a creature will drop a corpse item of itself. If no corpse item exists for the chosen creature, then the next Shambling Corpse summoned by the necromancer will be one level higher.
Abjuration - Player tool that works similar to Taunt, but uses Spellcraft and applies a much lower value of spell failure. Bonus on disrupting Druidic Rituals.
As for how often they can be used.. not often, I'd say! Just figured I'd throw the idea out there.
I like the concept but would argue against buffing wizards.
Some of it is rather powerful, yes. Admittedly Conjuration doesn't need a buff, considering how powerful it is on its own, and how Specialized Conjurors already get a buff. Seeing more boons, flavorful or mechanical, would just be nice for the less-taken fields of magic.
Divination, Enchantment, and abjuration ought to be added!