Kevin Schroeder has posted excerpts from the sixth and seventh chapters from his "You Want To Do WHAT With PHP?" book.

Chapter 6 focuses on asynchronous processing and the excerpt talks about doing it with a little big of encryption on the side.

In the excerpt from Chapter 7 he looks at a more structured way to access files rather than just the random fopen or file_get_contents. There's a code example in this one showing how to get the header information off of a file for things like file type, last modified time, a header checksum and the file's permissions.