Agora is a reflective prototype-based object-oriented programming language that is entirely (and solely!) based on message passing. http://progwww.vub.ac.be/pools/agora/
Omega is a pure object-oriented programming language developed by Günther Blaschek. Omega is a pure object-oriented programming language based on prototypes programming paradigm http://infosoft.soft.uni-linz.ac.at/Info/Omega.html