Start your own toy library!
John Rosemond, a psychologist who has a column in the Valley Times, has a great idea to help parents deal with toy clutter, and make clean-up time the responsibility of the child.
He says that clean-up time is such a problem because the children have so many toys to deal with. "Regardless of how many toys your children have, give them access to no more than five. Keep the rest in a "toy library" over which you have complete control. In order to check a toy out of the toy library, one of the children must turn a toy in. This means that they will never have access to more than five toys at a time, a number that should present no problem when it comes time to pick up and put away."
I would add a suggestion to his idea, because I could picture my own kids expecting me to be standing next to the toy library at all times, ready to switch toys revolving door style. I suggest toys be selected once in the morning and once after nap, or when it seems reasonable to the parent.
Joyful Noise does a version of the toy library here at school. We have scads of toys hidden in closets and get a selection our every Monday. We clean up every hour or so and put toys on shelves so the next class can take out and clean up their own messes. Sometimes on Friday there is something "new" to keep interest up, but we have found that too many toys leads to kids just dumping out and walking away! A new selection comes out next Monday.