This is the best introductory, conceptual article on Lisp I’ve ever seen. It’s written by Slava Akhmechet.
Lispers have long felt that it’s very difficult to get lay programmers to understand Lisp, because there’s no common context to help people relate to its unique syntax and powerful features. Slava went against the grain and managed to pull it off. His message is “XML = Lisp with angle brackets”. Or, put another way, “You’re soaking in it!” Are you using Ant? Are you using Hibernate and/or Spring? Are you using CodeSmith to generate code? If so, then you are already halfway to understanding Lisp, because even though the syntax is different, the underlying concepts are the same. XML is your code, and the XML processors are analogous to a Lisp interpreter running your code against some pre-loaded libraries. The difference is Lisp gives you more flexibility and control (ie. more power).
If you don’t understand Lisp macros, but you know how to program in C/C++, he helps you make the transition from C/C++ macros to Lisp macros.
He sums it up with: “Lisp is executable XML with a friendlier syntax.”
Once you understand these analogies, he introduces you to Lisp code.
If Lisp has mystified you, this is a great introduction that will help you get on your way. It won’t make you totally comfortable with it right off the bat, but it will help you get over the initial comprehension barrier. To increase your comprehension, and to learn what Lisp can really do, the following books have come highly recommended to me. I must admit I haven’t read them yet: On Lisp (online book), by Paul Graham; and Practical Common Lisp (online book), by Peter Seibel.
Some others that cover Scheme, a Lisp dialect: The Little Schemer, by Daniel Friedman; and Structure and Interpretation of Computer Programs (aka. “SICP”, online book), by Harold Abelson, Gerald Sussman, and Julie Sussman.