This isn't creative in itself, although I'm certain one could find creative uses for it. One of the most potentially abusable spells IMO is Simulacrum. This requires a caster of at least 17th level who can cast Wish and a caster who can cast Simulacrum (or Wish, if you have two casters who can cast Wish).
1) Create a simulacrum of the 17th level wizard using Simulacrum (or Wish, if you have a second caster capable of doing so).
2) Have the simulacrum create another simulacrum of the 17th level Wizard by casting Wish.
3) Have the new simulacrum create another simulacrum. Repeat.
You now have an inexhaustible supply of high level wizards, get as creative with that as you will (Council of Ricks?).
As has been stated above, this is highly contingent on the DM allowing such shenanigans (I wouldn't), so caveat emptor.
For an actual creative use, one time the party was ambushed by vampire brigands in a dense forest during the day. They grappled one of the PCs. The low level caster had no spells that would harm a vampire, so she used silent image to make it seem like the canopy had been parted just enough for a beam of sunlight to touch the vampire's hand. The vampire failed its save and recoiled, freeing the grappled PC.
Unfortunately, the rest of the party still died, but it was clever IMO.