I just bought this emergency washing machine from Emergency Essentials. It cost $14.95.
It looks a little like a plunger. (In fact, some survivalist books say you can use a clean plunger. But this one has been engineered to do a better job on clothing- see the grill? That keeps the clothes from getting sucked up into the plunger, and creates a vacuum to pull the water through the clothing better.)
You take a 5 gallon bucket and cut a hole in the lid for the handle to stick through. Put water and some laundry detergent in the bucket with the clothing, and beat the clothing like you are churning butter. (If you don't have a lid with a hole in it, you can churn it without a lid, but you have to be more careful not to slosh the water.)
I think it looks like it would do a better job than scrubbing on a washboard, which some of my boys had to do on their missions.
