Let Over Lambda by Doug Hoyte

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.

Common Lisp: An interactive approach by Stuart C. Shapiro

A textbook that teaches mainly through the use of exercises

The chapter on closures

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