Is it possible to replace Linux as the heart of serverless cloud computing services? That's exactly the intention of a startup consisting of developers from the open source Postgres database project ...

DBOS Inc., a new startup led by prominent computer scientists, launched today with $8.5 million in seed funding and an operating system designed to challenge Linux. Engine Ventures led the investment.

Looking for non-Linux open-source options? From ghosts of past operating systems to fascinating works in progress, here are my top picks.