My front wheel is fitted with Son hub dynamo from Schmidt which generates power while cycling. It does what its supposed to do and without any noticeable extra effort on my part(allegedly 0.5w when no gadgets are using power) at higher speeds the hub can generate up to 6W/12v. As the body is bigger than a standard hub it means you use shorter spokes making the wheel slightly more robust. The only downside I can find with the hub is the price, it adds about €150 to a standard wheel. Twice during the trip through Africa I had no power from the hub, a quick clean of the contacts on the right hand side of the hub fixed this.
Note to stupid people : don’t submerge it in water (river crossings) as it has a breather hole which will allow water into the hub.
When I’m away from town for more than 3 days I also use the hub/e-werk to charge my phone for a morning every other day (and have it switched off most of the time) this is enough to fully charge it again. The E-werk has dozens of settings an cables allowing it to power most things if you know what you’re doing. Recently they brought out a slightly cheaper USB-Werk which is actually more suited to most people like myself that mainly charge USB items, it also has a small internal battery which will keep a gps powered at a stoplight etc.
In the one year cycling in Africa I never wild camped more than one week straight so never needed to charge my AA batteries via the hub. For battery charging I use a small 2 cell Usb charger from Varta. I carried 6 AA batteries in total. 2 for the GPS, 2 for my torch and 2 in the charger as spare.
To charge my usb devices (phone/battery charger/ipod) I used a Belkin dual USB in combination with a local adapter that costs about €1 (rather than an expensive universal travel Adapter) and sometimes my laptop. That said for a similar trip I’d take the expensive all in one option next time, at one point I was carrying two bulky adapters and a multi plug. Having a dual USB charger is very handy when doing the sneaky charging in a petrol station thing, you can charge the phone and ipod at the same time .
Newer smart phones cannot be charged directly from a E-werk because the need constant stable power, therefore a buffer battery is needed or maybe the new USB-werk will do the job….