Self is a object-oriented programming language. It has a syntax is similar to Smalltalk but uses prototypes and delegation instead of classes and inheritance. The original Self system was developed by Sun Microsystems and Stanford University. Self4Linux is a port of the Self system to Linux.
Slate is a prototype-based object-oriented programming language based on Self, CLOS, and Smalltalk. Slate syntax is Smalltalk-80-based, rather than trying to be clever and complex. However, the language semantics, environment, and run-time design are all much more powerful than in traditional Smalltalk systems. The design goal is to bring together many excellent existing ideas into one system, and to provide an environment where design decisions in one area don't constrain others.