The XLISP scripting engine was embedded in a number of applications including, most notably, AutoCAD (as AutoLISP). What I didn't notice until last week is that XLISP is also included in Audacity -- it's the foundation for Roger Dannenberg's Nyquist, a "sound synthesis and composition language." I'd seen the plugin directory in my Audacity folder but never unpacked it until I was looking for a way to clean up a bad voice recording. Who knew? Those plugins are, for the most part, .ny (Nyquist) files, and they're written in a language that extends XLISP!