As a dm I had a player that used Create water to Waterboard his enemies.
I've had wizards Ghost sound fanfare to victory in battle.
I've had a rogueless party use Open/close on every door and chest, and one time they got a surprise round on a mimic.
As a player I rolled a druid who used create water and Animate water to assasinate an entire town. The water flows under the door and drowns people in their sleep (Coup de Grace)
I currently have a rogue that uses Prestidigitation (due to minor magic), to groom himself and flavor the clerics created food. Not to mention erasing tracks by cleaning the places he steps, also cleans poison from doorknobs. I must say, prestidigitation is one of the handiest and most versatile spells in the game.
I had a cleric in a SCAP game use a quickened (via a rod) create water spell to form a small pool of water to enhance a banishment spell against some fire elementals.