i get excited by pretty renewable materials and manpowered gear. of late there has been some information floating around about bike frames made with an interesting assortment of renewables:
beautiful wood frames (Cell is my fav)
Biomega’s biolove (though for the life of me I can’t find it on biomega’s site)
sandwich bikes the idea is you buy one, they export one to folks in need
Brano Meres homemade bamboo bike frame too hot!
Calfee Design’s bamboo bike pricey, but pretty. nothing like a bike that has to be wiped down with furniture polish.