Common Lisp.<p>The only tool I use with it, I guess would be emacs.  Unless by &quot;tool&quot;, you mean libraries.<p>However, it&#x27;s Ruby (often generated by Common Lisp) that puts food on the table these days -- and Python that I&#x27;m using to plot my (positive) escape from the workforce.<p>Both Ruby and Python are weaker languages that share some of the Lisp spirit.  Ruby in fact, is derived from Emacs Lisp.<p>One of my side projects is an attempt to jack libraries from Python -- which will, if successful, make Common Lisp more usable as a day-to-day programming language.