There's tons of really wild ideas in Interlisp that seemed to be the half-baked acid trip ideas of West Coast hippies at the time, that are just starting to become rediscovered in the past couple of years (pervasive undo -> reversible debugging, DWIM-like autosuggestions in more places), and even the implementation techniques used are still innovative (for example the error-trapping implementation of Conversational Lisp (http://docs.google.com/viewer?a=v&q=cache:4GnEnGS2XXkJ:c...) is quite similar to how Geoff Wozniak approached auto-defining functions (http://exploring-lisp.blogspot.com/2008/01/auto-defining-fun...)