As part of children learning the value of money, I believe it is important that they learn to earn their own money. While I could assign arbitrary monetary values to household chores such as cleaning, yard work, etc., I'd rather find something they can do with an objective monetary value. And I'd like to do so at as early an age as possible.
Yard-work is actually very close to what I'm after: I could have a child find out how much a lawn service charges and what services they provide for that, then propose that I pay them what I would otherwise pay (a competitively priced) service (less gas & machine upkeep). That's close, but then they could then make the same offer to others in our neighbourhood, and bring money into the household, and that would accomplish the goal.
What other possibilities are there? What about for younger ages?