ACL2 is a mathematical logic, programming language, and mechanical theorem prover based on the applicative subset of Common Lisp. It is an "industrial-strength" version of the NQTHM or Boyer/Moore theorem prover, and has been used for the formal verification of commercial microprocessors, the Java Virtual Machine, interesting algorithms, and so forth.
CL-BibTeX is a replacement for the BibTeX program, written in Common Lisp. The aim is to enable the user to format bibliographic entries using Common Lisp programs, rather than using the stack language of BibTeX style files. A compiler that transforms BibTeX style files into comprehensible Common Lisp programs is included.
CL-INTERPOL is a library for Common Lisp which modifies the reader so that you can have interpolation within strings, similar to Perl or Unix Shell scripts. It also provides various ways to insert arbitrary characters into literal strings even if your editor/IDE doesn't support them.