Challenges or achievements should be added to survival. These could be accessed with either the command /challenges or /achievements.
After completing challenges you could receive money, some block claims, or another item. Some challenge items:

  • Rewards for breaking a certain amount of a specific block,
  • Rewards for number of potions brewed,
  • Rewards for number of specific mobs killed,
  • Rewards for walking distances, etc.
This would overall just add more things to do on survival and another source of obtaining items.