Nice, I enjoyed Jim's talk where he derived the combinator using clojure[1]. In it he referenced another talk that he cites as an influence, "Programming With Nothing"[2] by Tom Stuart where he writes fizzbuzz in ruby using only lambda application.

Finding the SKI calculus was a similar revelation to me, that such simple combinators could represent any lambda term is such a huge idea!

1: http://www.infoq.com/presentations/Y-Combinator

2: http://rubymanor.org/3/videos/programming_with_nothing/