I have several pieces of electrical equipment which I consider indispensable for the trail.
My headlamp, my camera, my GPS, my PDA phone, my radio and my bluetooth keyboard (no way I'm gonna spend all night thumbing in my journal and mandatory email to family) The headlamp, GPS, radio and keyboard run off AAA, or AA NIMH batteries. The Camera and phone have lithium batteries.
I was wondering if I'd have to bite the bullet and carry a couple of chargers on long distance hikes, beg for outlets and wait around for batteries to charge. Then, pretty much simultaneously, I came across a lightweight solar NIMH battery charger and a do-it-yourself battery powered boost supply that can charge any device compatible with USB power. (camera and PDA charge from USB).
The boost supply (pictured) is a VERY simple $20 kit that anyone who can read and has a soldering iron can assemble. It can be located on the web by googling "minty boost". The minty comes from the Altoid tin the plans call for to hold the assembly. I didn't bother with the tin which I regarded as dead weight, and I replaced the two-battery holder with one that holds four and has a switch on it so I don't have to remove a battery to shut it off.
Assembly took 20 minutes. Checkout took 30 seconds after which I charged my camera with it.
The solar charger is an off-the-shelf Silva flexible panel (4oz.) that hangs down the back of my pack. It takes about 2.5 days to charge two AA's in sub-optimum winter conditions. I reckon it will take less than a day in the summer sun.
This might not seem all that good, but with the exception of the GPS which I keep for emergencies and have yet to turn on, all my electronics can go for days or weeks on a charge, so I think I can get by with a few extra batteries charging whenever there's sun.