Handing each child a cleaning rag and a spray bottle of water or diluted cleaner (depending on their age), I told them they had three minutes to get their white rag as disgusting as possible. I learned to tell them the boundaries of where they could wipe (Teddy figured out early on that the rag would get extremely disgusting by running along the track of the sliding glass door). Then I would stand back and watch them squirt and wipe their hearts out.
The best part would be when they would squeal with glee at finding a particularly disgusting glob on the floor (this is revealing way to much info about the state of my home!).
When the timer sounded, they would lay out their filthy rags for inspection. The winner would receive 5 M&Ms or marshmallows, while everyone else would get 3 for effort. If the floor needed more work, we'd set the timer again. Fun, laughter and a floor cleaned in minutes!