Common Lisp: An interactive approach by Stuart C. Shapiro

Paradigms of Artificial Intelligence Programming by Peter Norvig

Lisp code for the textbook "Paradigms of Artificial Intelligence Programming"

Common Lisp Koans

Common Lisp Koans is a language learning exercise in the same vein as the ruby koans, python koans and others. It is a port of the prior koans with some modifications to highlight lisp-specific features. Structured as ordered groups of broken unit tests, the project guides the learner progressively through many Common Lisp language features.

Let Over Lambda by Doug Hoyte

An advanced book on Lisp Macros

The chapter on closures

Has several non-trivial examples, and demonstrates the power of this feature