Copyfarleft
Copyleft with a class clause: free for worker-owned cooperatives and non-profits, but not for ordinary firms that employ others.
The idea comes from Dmytri Kleiner, set out most fully in The Telekommunist Manifesto (2010). His argument was that ordinary copyleft favours whoever holds the capital: a large company can build a profitable service on free code just as easily as a hobbyist can, and always ends up on top. Copyfarleft instead allows commercial use only by those who own their own labour.
The best-known implementation is the Peer Production License, based on CC BY-NC-SA, where the noncommercial restriction doesn't apply to cooperatives and non-profits. It isn't OSI-approved and is rarely used for software – but it asks the question permissive licences never have to answer: who actually profits from the code being free?