Bill’s got the trick for getting kids to clean up their toys:
This hack is aimed mainly at small children, since their toys are designed to take a beating. Also, not for the noise-intolerant.
To get my kids (3 and 5) to put their toys away (typically in some sort of toy box), we play a game I call "Bam!" which involves grabbing everything on the floor and hurling it into the toy box while yelling "BAM!" as loud as you can. They love it, especially if you join in the racket with them. Takes about 30 seconds to completely clean a 12 x 12 room.
You may want to explain to your children that this is for "at home" only, not during playdates, day care, kindergarten, etc, when others may not take this behavior the way it was intended.