Decaf was written for SBCL. It should also work with ACL.
License: GPL
Download: http://www.lichteblau.com/download/deleteme/cloak-0.1.tar.gz
decaf
Decaf is an Java debugger GUI written in Lisp using CLIM. The GUI itself is still rather prototypish, but the debugging library it is based on (CL-JDI) is mostly complete.