Battle mechanics like "trip", "disarm", "grapple", etc.

[Yankee]

What spells are Battle Cunning and Greater Battle Cunning are useful for?
It works for an attack roll, and according to D&D 3.5 rules the Ranged touch spells are also attack rolls. Such as various orbs, bolts, rays, beams, missiles.

[BlueSalamander]

It should be useful for all touch spells that deal damage dice, as then you can have critical hits. Cheers