Home currency to keep the kids under control.
(unfortunately we don't live together).
She's started a home currency using monopoly money.
The kids can earn money by doing their school work, helping around the house and so on.
They can spend the money on time with the X box or TV, sweets, ice cream and so on.
She's posted lists on the fridge of how much each "treat" costs (screen time is 300 per hour and ice cream is 40 for two small scoops), how to earn currency (for example 30 minutes reading gets them 100, cleaning their room earns them 50 and mowing the lawn pays 400) and fines (100 for throwing a tantrum, shouting, half a chore, argueing etc).
I think this is an excellent idea which deserves sharing