I spent some time with Self in the late 90s (at college of course!) and it was impressive on several counts: first, it's JIT compiler allowed Smalltalk to run faster when implemented in Self than without - the same JIT technique was later re-used in Java Hotspots [1]; second, the programming environment was a multi-user environment called Kansas that allowed a whole classroom of students to develop "prototypes" in the same environment (Kansas [2] [3])