Hemlock
Hemlock is an Emacs-like editor that comes with CMUCL (Debian users need to get the cmucl-source package). Why not take a CloserLookAtHemlock?

Looking for quick instructions on GettingStartedWithHemlock?

If you want to use Hemlock with an X11 server that uses magic cookies (eg, connections forwarded via ssh), and if you're using a CMUCL distribution from before summer 2002 (or so), you'll need to load the following patch: Make Old CMUCL CLX Work With Magic Cookies.

See also cl-emacs, I guess.

Portable hemlock. There is an attempt to free Hemlock from its CMUCL prison and port it to ANSI CL plus CLX called the Portable Hemlock. It has already been persuaded to run on OpenMCL and SBCL, and possibly others.

A recent version of hemlock is available through git (based on the portable hemlock codebase):

git clone git://gitorious.org/hemlock/hemlock.git

For more, see the Hemlock wiki on gitorious.