It supports Xanalys LispWorks, CMUCL, MCL, OpenMCL and Corman Lisp.
You can find it at http://sourceforge.net/projects/portableaserve.
AllegroServe (formerly Allegro iServe) is a LLGPLed Web server which is designed for use with Allegro Common Lisp.
AllegroServe has a public repository and online documentation that includes a tutorial.
NOTE - Portable Allegroserve does not appear to be maintained. The sourceforge mailing list is inactive. The http client package appears to suffer from a chunking bug that causes it to corrupt retrieved pages. Hence the Hunchentoot server and the Drakma client may be preferable for new projects.