Phone straps and decors are very popular in Japan, but this is probably the most useful strap I?ve seen. The Strap-Ya sucks light source all day, and stores the energy in its built-in battery. It charges your phone when you plug it in. Six hours of sunlight will get you about thirty-five minutes of use.
The good news: It?s only $17. The bad news: It?s only for Japanese phones.