In a design of the Yoyo concept phone, ModeLabs staff was inspired by the traditional toy. Born from a hybrid energy idea, this concept device powers itself using the solar and kinetic energy. Furthermore, the Yoyo concept uses photovoltaic cells, pendulum with circular movement and the retractable headphones that trigger pendulum motion. Alphanumeric keypad is placed around the handset, and the device have the sensitive keys.
I love the idea. Just imagine charging your phone by playing with it.