The Python Standard Library is an extensive library. Most of the time, this library will have what you are looking for. This is referred to as the "batteries included" philosophy of Python. I highly recommend that you go through the [Python Standard Documentation] that comes with your Python installation before you proceed to start writing large Python programs.
Python.org - The official site of Python with comprehensive information regarding Python. You will also find the latest versions of Python here. There are links to various mailing lists where active discussions about Python take place.
comp.lang.python. This is the Usenet newsgroup where discussion about this language takes place. You can post your doubts and queries to this newsgroup as well. You can access this online using Google Groups.
Python Cookbook is an extremely valuable collection of recipes or tips on how to solve certain kinds of problems using Python. This is a must-read for every Python user.
Charming Python is an excellent series of Python-related articles by David Mertz.
Dive Into Python is a very good book for experienced Python programmers. If you have thoroughly read the current book you are reading ("A Byte of Python"), then I would highly recommend that you read "Dive Into Python" next. It covers a range of topics including XML Processing, Unit Testing, and Functional Programming.
IBM DeveloperWorks - you will find interesting articles such as Grid Computing using Python .
O'Reilly Network - here you will find the latest Python news.
Python at O'Reilly - this is an exhaustive resource containing many Python-related articles.
Google - the ultimate search engine for the ultimate dynamic programming language (Python)! Also take a look at the Google Jobs website which lists Python as one of the pre-requisites for qualification for a software engineering job at Google.
Jython - this is an implementation of the Python interpreter in the Java language. This translates to using the expressiveness of the Python language with the extensive Java libraries. For example, you can create Swing GUI applications using Python code.
IronPython is an implementation of the Python interpreter in .Net/Mono. This translates to using the Python language along with the powerful .Net libraries. IronPython is from the same person behind Jython - Jim Hugunin.
Lython is a LISP frontend to the Python language. It is similar to Common LISP and compiles directly to Python bytecode which means that it will interoperate with your usual Python code as well.