I tried to avoid overlap with my earlier post on the Lyre of Building. Keep in mind it doesn't have to be a wall. It could be a floor, ceiling or other stone object.

Acid Arrow creates a wall that burns everything that it touches. Similar traps include Bane, Chill Metal, Confusion, Mass Hold X, Wall of Fire and for undead, Sunbeam.

Animate Dead creates uncontrolled zombies out of those who die and come in contact with the wall.

Dream allows passing along the message to all those who sleep in contact with the wall. The message could be hundreds or even thousands of years old. Hopefully it wasn't placed there by an aberration...

Explosive Ruins in synergy with Fireball and Wall of Stone makes for a lethal trap that can kill a small army. As long as they are close enough to the wall to read the rune, that is.

Fabricate allows the caster to shape the resulting stone into all kinds of forms. Together, these spells can create a building or reshape dungeons with but a few castings.

Floating Disc makes walls that are initially in mid air or in shapes that the wall can not form alone. When the disc spell ends, the wall comes down.

Quench keeps fire from damaging the wall. It also is useful in containing fire elementals, at least until Quence ends (one hour per caster level).

Spike Stones can be used to stop an calvalry charge or creatures using the wall to climb to the party.

Stone Tell, with Fabricate and Wall of Stone can create a spying mass of mineral that can enter an enemy encampment and relay information about the enemy. Of course the enemy can also use Spot checks to notice the ribbon of stone appearing even if it looks like the surrounding ground.

Transmute Rock to Mud could be used to make soil, but most casters use it to hide something quickly under all the dirt. Add in Plant Growth and small hills can be created that look like the surrounding landscape.