ILISP is a Emacs based interface to various lisp-like systems - a pretty essential Development aid. It's available at SourceForge, and packaged for Debian. Instructions for making ILISP work with Emacs under Windows or Mac OS are found at the Common Lisp Cookbook here.
I'm finding ILisp a bit confusing. I think I have it installed in Emacs for CLisp and CMUCL, but when I try to edit files I think elisp is still in charge, e.g. the error handling after evaluating (/ 1 0). How do I get CLisp to "kick in"? I've copied the ilisp.emacs to .emacs and changed the various paths.