The required textbook for this course is
ANSI Common Lisp
Paul Graham
Prentice-Hall
ISBN 0-13-370875-6
Ignore the very misleadng title. This is not a reference on the Common Lisp standard. It is an introductory text, with some great example applications, and an up-to-date complete glossary of all Common Lisp functions and special operators.
Commentary (expansions, disagreements, challenges) by yours truly on various items in the book can be found here.
The serious Common Lisp programmer also needs to own a copy of
Common Lisp The Language
Guy L. Steele Jr.
Digital Press
ISBN 0-13-151507-1
This is the standard reference book, and is also available on-line, but not the definitive standard. That's the ANSI Common Lisp standard, which is available on-line in Kent Pitman's Common Lisp HyperSpec™.
The EECS 325 Newsgroup is the place to get announcements, ask for help, and give help. See Reading the EECS 325 Newsgroup for details on how to set this up.
There are two recommended versions of Common Lisp for this course:
I test the code I distribute on Allegro and LispWorks.
In addition to Lisp, you also need to download Lisp code from the EECS 325 code library. Various setup tasks and exercises will tell you what you need. If I change any of these files, I will post a notice to the CS 325 newsgroup telling you to get the new version.
The EECS 325 code library contains many additional pieces of Lisp code, including utility code, project code, and all the textbook code that appears in the main figures, downloaded from Graham's original source file.
Comments? 
Send me email.