There's something really cool about adding servers to a borg by tossing them into the ocean. Imagine a solar powered buoy with some compute and storage, with full connectivity to the internet, just floating around in the ocean. And then imagine millions of them all collectively forming a decentralized cluster.

Maybe it's just me, but I think that'd be awesome! The limiting factor is power efficiency and battery tech. Of course maintenance would be a problem, but not with fault tolerant clustering designs. And there's the ecological issues of tossing hardware into the ocean, but at least there's no need for a cooling system...