cl-ppcre
CL-PPCRE is a portable, Perl-compatible regular expression library by Edi Weitz.

CL-PPCRE was also used to implement The Regex Coach.

Darcs repo:

http://common-lisp.net/~loliveira/ediware/cl-ppcre

Github:

https://github.com/edicl/cl-ppcre