As the use of your mobiel phone increase, the battery life time gets shorter. A specially on vacation you do not always have the right charger for your mobile phone. Tha answer The Solar Charger. Many manufactures produce such a product and many of those has their own explaning why there product is the best. What does matters are the numbers. A regular mobile phone usses 4.5 V and about 1 mA (or 1000 mA).
Important features are the onboard battery so you can recharge when yoou need it. You have also some chargers who are water resistand or who also can use wind energie. Almost all the chargers have plugin converters for the right type phone of MP3 player. See for more information the link under the name of ther charger.

Name	Euro	Battery	Rated output	Output	Recharge	Size (mm)
A-Solar Power charger	44,95	Lithium Ion	5.5V/7.5V/9.5V	2000 mAh
A-Solar iPhone Solar Charger	28,95	Lithium Ion		800 mAh
A-Solar Dual Panel	38,95	Lithium Ion		1200 mAh
GP Solar	19	Lithium Ion	4.2V 150mA			180x110x60
Solio Magnesium edition	120	Lithium Ion	8 W	0,85W 5,5V 150mA	3.7V 1800 mAh	120x65x34
Solio Classic Universal Hybrid Charger	70	Lithium Ion	4-12V 0-1A	155mA 6V	3.6V 1600 mAh	119x33x63
Solio H1000 Universal Hybrid Charger	56	Lithium Ion	1.5-5W	0.6W	3.7V 1000 mAh	198x68x18
K3 charger	July 2009	Lithium Ion	5V 1A	5W*	3,7V 4000 mAh	78x236x80
Amorphous Si panel	14	No	1.5W	120mA 12V	12V
powermonkey-eXplorer	73	Lithium Ion	4.5V-5.5V	700 mAh 5V	2200 mAh	90x45x38
solarmonkey	40	No	5V 240 mAh	240 mAh	110x70x10
Solargorila	156	No			500 mAh	264x200x19

Price's are from 7 juni 2009.