Shaving cream is one of those beautiful little things I love my children to play with. When I put it on the table and they write letters and words in the squishiness, it ends up cleaning my table like nothing else can (WARNING: It might not be good for certain wood stains).
Obviously shaving cream is a perfect bathtub toy, too. I like to get out a muffin tin, fill it with shaving cream, mix in some food coloring and hand it to the kids with a paint brush. They'll spend 30 minutes "painting" my bath tub walls. And when I wash of the artwork, my walls glimmer.
Child labor that's fun? Winning!