Micro Web Walker is a very simple web walker written in Allegro Common Lisp. Dale Steeber and I wrote this walker in two days. I used it several times in my classes to get students started on doing web stuff in Common Lisp fast. John Mallery's CL-HTTP, a HTTP server written in Common Lisp, provides a much more sophisticated constraint-based web walker written in Common Lisp.
A quick readme can be downloaded from here.
The zip archive with the source code and documentation can be downloaded from here.