A Byte of Python is nominally available for free as a web-based book, but is also available as a PDF download and in printed hard copies. Many translations to languages other than English also exist.

A Byte of Python Swaroop C H's online book offers many, many little knowledge chunks. Each page offers a tiny bit of Python knowledge, with clean formatting and good examples.

He is also the author of Gray Hat Python (no starch press, 2009). If you’re truly interested in information security, Python is the language to learn and this book should be added to your library.

An old Python in a Nutshell book did fine for me. It only covered up to 1.5.2 (checked it out from the library) and I was able to pick up the new stuff in 2.x,2.2,2.3,2.4 from just working with ...