I will try to add to this every day.
So far I've had:
The gong takes technology (some tech points were taken, but not more than 40000)
The gong grants health (no one got sick or lost health for ~3 hours. Tried to use the death stew, but no one would die and the healers had a field day)
The gong takes food. (some food was taken, but not more than 20000)
The gong grants wisdom. (the villager who rang the gong went from 0 to MAX on builder)