Knowing we had some time to kill on Sunday, I wrangled us tickets to the ANME Winter Expo being held in Las Vegas. It is for those in the military surplus business and featured everything from knives to all sorts of surplus gear to camping supplies.
One of the coolest and least expensive things I found was the Simple Shower. It converts a 1 to 2 liter bottle into a handheld shower. Unlike the black shower bags, the temperature of the water never gets too hot. Setting a clear 2 litter bottle of water out in the sun for a couple of hours will raise the temperature to about 102-104 deg. which is plenty warm for a shower.
The kit includes the shower head and two tubes. You attach it to any water bottle, let it sit in the sun for a while, and now you have a warm shower.
The patented Simple Shower weighs less than an ounce and costs about $10. I think designer James Peet has a winner on his hands. You can order it directly from the company at this link.