Hunchentoot is a web server written in Common Lisp and at the same time a toolkit for building dynamic websites. As a stand-alone web server, Hunchentoot is capable of HTTP/1.1 chunking (both directions), persistent connections (keep-alive), and SSL, but it can also sit behind the popular Apache using Marc Battyani's mod_lisp.
Hunchentoot provides facilities like automatic session handling (with and without cookies), logging (to Apache's log files or to a file in the file system), customizable error handling, and easy access to GET and POST parameters sent by the client. It does not include functionality to programmatically generate HTML output. For this task you can use any library you like, e.g. (shameless self-plug) CL-WHO or HTML-TEMPLATE.