This is a 1/10th scale model of what is eventually intended to be a 90m autonomous airship that can generate its own hydrogen (for buoyancy and fuel) from rainwater. It's mostly an art project now, but the vision is inspiring. Arduino-powered, of course. That reminds me that we have to design Blimpduino 2 later this year. I miss blimps!
Good interview and write-up here.
Here it is flying: