Light Table is very interesting (I've used it for some Clojure stuff), but it's competing with emacs. It's gonna be very hard to beat emacs. The legacy of thousands of lines of very useful code & unbelievable extensibility is a big one to overcome. I don't mind saying that I foresee emacs getting a lighttable-mode for dynamic languages before Light Table beats emacs. But I usually have a LightTable install on my computers; it's that promising of a project. :-)