One which basically says the following: 1. This work is free (to use and distribute), will always be free and can never be used as part of a proprietary system. 2. Everything extended from it is free (like the GPL) 3. It cannot be used with commercial software 4. This software cannot be linked to or interface with commercial or proprietary software. So basically, if you made a script like WordPress or phpBB, any software made to extend it (or made to run alongside it) would have to be under the same license and loopholes like the 'GPL PHP and non GPL CSS/images' thing would be impossible. Does a license like that exist?