The idea of using Emacs lisp for scripting was introduced to me he on hacker news, and it's not a bad idea. In service of being a good extension language, Elisp has a lot of really handy built-ins. There aren't a lot of Elisp language extensions, but you can often pluck good functions and macros from existing packages. For scripts with more than a few lines I like to use CL, but that's after building out a pretty large utility library specifically for the task.