Pylons is a lightweight web framework
emphasizing flexibility and rapid development.

Pylons is a lightweight web framework built on standard Python tools that provides a robust environment for writing modern web applications. It is well known for its clean architecture and loosely coupled approach, both of which make web development fast, flexible, and easy.

Pylons users have long called for a definitive guide to the framework that pulls together each of its components into one easy-to-follow manual. I’ve written this book in response to that call. Whether you work with Linux, Windows, BSD, or the Mac OS, this book will teach you everything you need to know about web development with Pylons—from how to create your first “Hello World!” application to how to use each of Pylons’ core tools including FormEncode, Mako, SQLAlchemy, and Routes to how to perform more advanced tasks such as testing, using Unicode, internationalizing your application, authenticating users, and more. I’ll take you through the intricacies of so-called WSGI middleware components and explain Pylons’ internal architecture step-by-step so that you can take full advantage of its features.

This book is filled with useful examples and code snippets to complement the text. Throughout the book you’ll be developing a complete Pylons application called SimpleSite, which will serve as a fully functional hierarchical wiki with facilities for comments and tagging. Through this application I will demonstrate how you can apply Pylons concepts to a real application, and I will give you all the knowledge you need to go on to develop your own applications. If you have never used Pylons before, you’ll find this book will serve as a great introduction to the framework, and if you are already an experienced developer, you’ll get fresh insight into Pylons’ more sophisticated features. 
http://pylonsbook.com/ 
http://pylonshq.com/