This may seem silly, but I really have to sing the praises of the Python Cookbook, 2nd Edition. Everybody else has known about it forever, but I just got my copy a month ago.
I am blown away. I can't believe how good this book is, far beyond any other programming book I've ever known. I'm now completely embarrassed about the quality of the code I wrote without it, and tempted to stay up all night refactoring everything. In fact, I've already largely rewritten sqlWrap.py based on what I've learned.
I'm afraid I dawdled about buying my copy because I never found the recipes at ActiveState all that compelling - occasionally nice, but usually nothing to jump and scream about. I figured the Cookbook would just be a bunch of them, bound together. Not so - the careful selection and excellent discussion make it amazing. It's like having a master programmer at your elbow to guide you.