If you're thinking of getting the annotated version, another classic in the same spirit is The Annotated Alice by Martin Gardner. It exposes a lot of double entendres, mathematical games, and other historical stuff about Alice in Wonderland that shows how much of a playful mathematician Lewis Carroll was.
Tuned In - great book, describes how to really understand user perspectives as opposed to 'inside-out' development.
The book's based on many principles taught in the Pragmatic Marketing prodm course.
Inspired (Marty Cagan) - good cross section of PM, covers People, Process and Product separately. Startups to large companies.
The Art of Product Management - a series of articles, describes software PM in startups to larger companies. More about the role of PM rather than product itself.
Rules for Revolutionaries - Guy Kawasaki's book, half entrepreneur morale book and half how to create a product quickly.
--- Blogs ---
Cranky Product Manager - crankypm.com
Silicon Valley Product Group - svpg.com (Marty Cagan's blog)