What is 'CLISP'?
CLISP is a fully functional cost-free implementation of ANSI Common LISP, available for both Unix and Windows machines under a GNU GPL license.
You can embed CLISP programs into commercial applications.
It's a great way of finding out more about LISP, or may work as a less costly alternative to other LISP implementations. (Other implementations of ANSI Common LISP, including personal and trial versions, are available from Franz and Xanalys)
You can find out more about CLISP from the website at clisp.cons.org