The eXtensible Language: easy to use, multi-syntax, portable set of APIs to create CLI and GUI applications for Unix/X11 and Win32; will ease making big applications, has interpreter/compiler/debugger. [Open Source, GPL]
A collection of information about Emacs providing links to Emacs related papers, Emacs lisp developer sites, notes about emacs debugging, package pointers and installation tips.
An exTENSIbLE programming language intended mainly to process text documents in various input formats and languages. Core uses only features from ISO C + POSIX library functions. Was NSL. [Open source, GPL]