Used to be called ArmedBearLisp.
The weird part about it is that the lisp interpreter is well hidden inside a java text editor, J (a BadName? for software, if you ask me). You can run it stand alone this way:
java -cp j.jar org.armedbear.lisp.Main
I am trying it out currently. It is a good idea, because you can call the java libraries (which are BIG), and makes ABL portable, two of my main objections about Lisp. See WhyWeHateLisp. -- JuanPabloNunnezRojas.
Recently (during the summer of 2004) I used ABCL to develop scriptable test tool for a communication library written in java. With ABCL just coming into its own it wasn't as pleasant as it could have been, but I was still impressed by the long strides it made in a short time. It is an almost complete CL implementation. With its active and responsive developers, I can recommend trying it out.
One of the OtherLanguagesForTheJavaVm. See also ClojureLanguage.