I've tried to convince my wife of this for the in-home daycare.
A velcro wall, you put all the kids in some type of harness when they get there foer the day, and then have a velcro strip like 3 feet off the ground (high enough to keep them off the ground, low enough that no one dies from the fall)
When the kids need a timeout, you just grab them by the harness and smack them onto the wall. Granted you'd need good velcro or something to assure that they cannot push off, but it seems like it would solve so many problems.
This is why I don't work with children