white noise generator:
https://www.electro-tech-online.com/threads/white-pink-noise-generator-on-a-9v-supply.105819/
im a cheeky b@st@rd. ;-)
if you have any lm386's (which are audio amps and not really op-amps) you can do a whole mess of things.
Square wave generators. Oscillators. ipod speaker amp. etc.
Check out the datasheet of the lm386 for some simple ideas.
Try the datasheet for a 741.
Or check out "ic op-amp cookbook" by Walter G. Jung.
TONS OF IDEAS AND APPLICATIONS!!!