Japanese papercraft sculptor Takahashi Masakazu makes all manner of lovely things (especially robots!) out of recycled consumer packaged goods packages.
Junkbot artist Andrea Petrachi has the true gift for conjuring the inner friendly robot from random piles of techno-detritus. A rare and increasingly valuable skill.
Dark Roasted Blend has a fantastic roundup of junkbots and other robotic ephemera and goodies. I'm really taken with Ultrajunk's creations, which really take advantage of the decay and use-marks on his found-object materials to make robots that have a lot of texture and implied history.
On Wired's Gadget Lab, a gallery of sculptures made from dead hard-drives made by sysadmin Miguel Rivera, including this wonderful junkbot.