The SODIS method only works if you're within 30 degrees of the equator, I think.

Cut the tops and bottoms off several, make one full-length slit in the side, and line them up to form a splint for a broken arm.

Cut off the top half and use the bottom as a cup or scoop, and the top as a funnel... if you need a funnel.

All of this assumes the bottles are either 'fresh' or haven't been sitting in sunlight for very long, or they'll just shatter.

Sue