How's this for versatle? The HYmini from miniWIZ lets you store energy in its 1200-mAh internal lithium-ion battery so you can charge your other myriad portable devices -- only it can get its juice from the sun and wind. Hang the $49 HYmini from your bike or mount it outside your car window to use the wind generator; attach optional solar panels (they're $24 each) to put the sun's rays to work; or just plug the thing into a wall socket or USB port. In any case, the result's the same: Connect the HYmini into, say, your MP3 player, and it delivers the power your hungry gadget needs. The only flaw: the HYmini's battery isn't removable, so when it finally gives out (the company estimates it has 500 complete discharges in its life) you have to replace the whole thing. That makes the HYmini almost, but not quite green enough.
Well, with 1200mAh you can't charge anything serious really. It will barely work for PDAs, GPS and Blackberries alike. It will work ok on the regular Razor-type cellphones only. I tried them all pwermon(k)ey, burnton and finally have chosen icetech solar i9005. It has immense 2850mAh. When fully charged it will charge stamy Verizon PDA over 4 times from 0 to full. Can't compare to anything else really. Plus it has a switch from 4.5 to 9 V - so it charges your device more effectively and (most importantly!) saves the life of your phone's/mp3's/mp4's,/etc.. Li-Ion battery!! Very few are aware that blunt unadjusted 5V charging performed by all other chargers on the market i have tested - will eventually harm your device if it needs 4.5 or 6V. Another neat perk for the nerds - i9005 also has a built-in ultrabright LED light, - you'll go blind for a bit if you look straight in it. All that splendor for $89.99 only. And if you are short on money try icetech i101 for $29.99. Just my 2c.