Lisp Symbolics Macivory 3 with loaded software
I believe that the user experience from this system, and similar, can be equally attained with other languages.  Of course, Lisp all the things, and I will agree there is no need of any other language, if that is to be argued .. but!<p>We could surely build an execution environment (which is what this is) with some other of the newer languages, broken as they may or may not be.