Dutch firm Soldius has deleloped a very portable solar charger for, well, your portable devices. 5 by 3 inches, the devices is small enough to toss into your back pack and should last, according to the company, for 90,000 charges (more then enough for a life time).
The device is called the Soldius1 and its provide a varying charge depending on the plugged in device. According to Solidius you can use your devices while plugged in.
The solar charger for an iPod or cell phone starts at $109, and “comes with the solar pad, a mini USB cable, two interchangeable iPod adapters compatible with the iPod, iPod Nano, iPod Mini and iPod Shuffle, as well as five interchangeable mobile phone adapters.” For just the iPod only kit expect to pay $99.99, and for just a cell phone charger kit expect a price tag of $89.99 – the combo kit sounds worth it.