CMUCL
CMUCL is a high-performance, free (mostly Public Domain) Common Lisp implementation that aims towards ANSI compatibility and runs on a number of Unix platforms - including Linux/ix86, Linux/Alpha, FreeBSD/ix86, NetBSD/ix86, OpenBSD/ix86, Solaris/SPARC, HP-UX/HPPA, and IRIX/MIPS - though not all of these ports are current. See the project home page at cons.org for more information.

Debian GNU/Linux users will find that their distribution includes CMUCL packages (Stable version, Testing version, Unstable version) which they can grab using apt-get. More information about the CMUCL port to Debian can be found at CMUCL on Debian. Other Linux packages are listed here: https://pkgs.org/download/cmucl

The EncyCMUCLopedia is a collection of most - if not all - of the documentation related to CMUCL. It is updated a couple of times per year. The latest version is June 17, 2001. The Design of CMU Common Lisp documents internal details of the CMU Common Lisp compiler and run-time system. By Robert A. MacLachlan (ed), updated January 15, 2003.

Not sure anyone besides me has had a problem with this, but I just thought I'd mention that if you set *print-lines* and/or *print-right-margin* to sufficiently low values, error-messages may show up as just "..", which is quite confusing. Oh, and if something is weird, remember to try without your super-tweaked init.lisp-file, like I didn't. (lisp -noinit)

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