PHP{Con West
I will be speaking at PHP{Con West this year about how to write a PHP extension. It will be a 3 hour tutorial, so I will be able to go through the whole process and even talk about some of the "black magic" that goes into some of the more advanced features of the PHP/Zend extension API.
I'll also be hanging around at the Code Sprint, not necessarily coding, but available to answer any questions you might have about PHP (preferably internals questions!).