Squeak.org

Squeak.org- Free, open source, open research, super portable, new Smalltalk-80-based language, written in itself, by Smalltalk's inventors, the (nomadic) original Xerox PARC, Alan Kay team, now founding the Viewpoints Research Institute. Runs on 22+ platforms, hardware and OS. Now hybridized with the Self language's Morphic User Interface Toolkit.