alt Hacker NewsThe second best book about Pure Data, so I've heard.
[ Yes Miller, that's fighting talk round here too :) ]
Seriously, this is a very very good place to start learning audio DSP in general because you hit the ground running, making sounds you can compose actual music with right away.
What is the best book?
Don't think I would call this about PureData, it just uses PureData for examples and the knowledge it provides is more general.