My favorite technical book of the past year was Practical Common Lisp by Peter Seibel. Believe me, if it could convince me to return to Lisp, it's a well-written book.
However, all the cool kids are learning Ruby. Ruby has some Lisp-like flexibility in comparison to more popular languages like Java and C#, but it doesn't have Lisp's elegance / terseness of syntax. If you want to learn Ruby, the best book is Programming Ruby: The Pragmatic Programmers' Guide, Second Edition.