in reply to Which non-Perl books made you a better (?:Perl )?Programmer?
For a domain specific book, I can't recommend Advanced Programming in the UNIX Environment enough. It not only helped me understand standard *NIX facilities, but it has great programming practices throughout. For a general programming practices book, I recently picked up and love The Practice of Programming. I wish I had seen the book when it was published in 1999. Each chapter ends with a "Suplimentary Reading" section that has promising titles.
-- Douglas Hunter