M0zza
I tried the powermonkey explorer - wasn't too impressed, it seems to need to be outside in full sunlight to charge up.
I've got both of these
http://www.powerbee.co.uk/Solar-Camp...-Pro/p-84-356/
http://www.powerbee.co.uk/Solar-Camp...rger/p-84-383/
and they work much better in UK weather through double glazing, also both come with a PSP tip which charges my PRS300 no probs (and my nokia, ds, dsi, mp3 etc)
Admittedly most of my gadgets were selected for long battery life but so far i've charged everything from the solar chargers (in winter I needed to charge the DSi XL a couple of times from mains).