I just rediscovered a pretty good Lisp tutorial - ELM-ART (german version, english version). My first contact was sometime early in 2003, when somebody else (could have been Rainer Joswig) gave me the link and I tried it out.

The whole tutorial is very well presented, and it includes exercises which you can solve interactively. The system also gives you feedback on errors in your code.

I found the whole ELM-ART (Episodic Learner Model / Adaptive Remote Tutor) concept pretty interesting, and found that the Uni Trier’s ELM group published a few papers on it. In case you’re interested, here are links to the papers that I could dig up:

• 1996: “ELM-ART: An Intelligent Tutoring System on World Wide Web” (html)
• 2001: “ELM-ART: An Adaptive Versatile System for Web-based Instruction” (pdf html)

Anyway. Don’t mind the underlying technology. It’s a pretty good low-level tutorial. Still, for a more extensive treatment of Common Lisp, you should get Peter Seibel’s Practical Common Lisp or Peter Norvig’s PAIP.