Enfucell's or Power Paper's flexible batteries has the usual thin n' flexible selling angle, but while still in development, are apparently anticipated to be particularly cheap and environmentally friendly due to a more off-the-shelf material and manufacturing process of metals in a paper and laminate sandwich. Sure, it may not produce a huge amount of juice, but when you're talking about very low-energy applications like e-ink, cheap, flexible batteries could power the digital newspapers of tomorrow before being thrown away with the day's rubbish.