This Kickstarter-funded software will let you design your own chair, share it online, and have it digitally fabricated using a service like Ponoko. A physics engine even tests chairs for stability and comfort.
Denmark’s Artificial/form has created the Valdemar Chair for Normann-Copenhagen. Fully upholstered, the Valdemar has fluid lines offset a bit by the open base and squat peg legs. Available in 4 colors.
The Lazy Bastard chair, by Bertjan Pot for Montis, is filled with polystyrene balls and covered in a knit fabric. The beanbag filling adjusts to any sitting position and fits like a glove for optimal laziness.