I apologize if this tip is obvious, but I've had a few friends comment that they liked this "idea".
When we're away from home bathing the kids I get frustrated, pouring cup-after-cup-after-cup of water over my children's heads, watching all the soap and dirt run into the very water they are sitting in, leaving them basically un-rinsed when we're done.
At home, we have one of those hand-held shower heads in our bathroom. After the kids have been shampooed or lathered up, I have them stand and I use the shower head to rinse them. Our tub actually has a bar so they hold on and lean back. Even my toddler complies. With our final rinse I allow the dirty/soapy water drain away to never-never-land, and my kids get out, all clean, happy and well-rinsed.