Wagan Tech inc has come out with a range of very conveniently sized (pocket-able) solar chargers for consumer electronics. They will charge batteries, iPods, digital cameras etc, all from the sun. The units themselves are very lightweight and come in two distinct types.
This is a fairly ingenious device that will let you charge a whole lot of different batteries in the one unit. It’ll do most all of your camera, cell phone, AA, AAA, AAAA and N sized batteries. The trick is in the way it clamps your batteries in place onto the moveable contact points, you have to adjust these yourself but it’s a fairly simple task.
Blue Spark Technologies produce printed carbon-zinc batteries, which are small, environmentally friendly and most importantly cheap enough to produce to make them viable. These batteries are also incredibly thin; their standard battery is 750 microns thick (that’s 0.75 of a mm), while their Ultra-Thin series of batteries can go as slim as 500 microns.