Designer Vivien Muller's Solar Cell Tree Charger takes a page from nature, using solar panels as leaves that'll allow it to soak up energy from the sun. Leave it by your window and you have a renewable solution for charging your gadgetry. It has space for 54 panels panels, and you can rotate them to try and get more output if you find something charging slow.
The Solar Cell Tree Charger takes a lot less upkeep than your average household shrub, too. Just, ah, don't water it. As smart as it is, it looks like Muller's tree is just a prototype.