Frame made out of bamboo, pictured here is a My Boo that touts a partnership with a fair trade social program in Ghana to make the frames.
It's supposed to be more ecological, for obvious reasons. Weight on one is about 15kg, which is pretty good for a kitted out city bike.
I can't speak to longevity of this and whether it actually pans out vs. say, a steel bike that you keep welding back together, on account of these haven't really been around too long. It's held together via a composite glue made out of hemp and resin, so at least they're following through here I suppose.
Reviews I've read is that the ride quality is really nice, being stiff yet compliant in the ride cases as to not make it a boneshaker.
Price of these is, obviously, fairly high, these'd run you around 3000€ euros, I'd argue a comparable bike made out of traditional materials would run you maybe 800€ new. But I'd argue it's more a proof of concept.
Calfree has been making them for the public since 2005