There are a lot of solar power packs out there, but this one, from Bootstrap Solar, has a lot going for it. First of all, it's particularly powerful, featuring a 5W monocrystalline solar panel (and room for a second). Secondly, it's inclosed in bamboo (which, for all its green credit, still raises concerns). Thirdly, it's sold as a DIY kit.
To assemble the Chi-qoo Solar Power Pack, you can buy the kit from Bootstrap Solar, or find the parts and go it alone- the design is open source. The whole process should take an hour or less. The 6.3in x 8.66in solar panel is powerful enough to charge a smartphone in 60 to 90 minutes. (For those planning to power iPads, a second panel is recommended.)
Using the device is simple enough: charge the battery by placing the panel in sunlight. Then plug in your phone, tablet, Kindle, whatever, and you're all set.
There are a bunch of upsides to making the Chi-qoo DIY. As Bootstrap Solar says, "Making stuff is fun!" The finished project comes with a sense of accomplishment, and it means that no factory worker was underpaid to do the work you put in. Plus, having built the thing, you're in a position to know how to fix it should something go wrong.
You can buy the Chi-qoo from Bootstrap Solar for $117 ($160 for a second panel).