Writing Apache Modules with Perl and C will allow you to enhance your Apache HTTP server in just about any way you'd like. Overall, it is an excellent book, and it has a lot of good information and terrific examples on everything from "Content Handlers" to customizing the Apache server configuration process.It's quickly apparent that Lincoln Stein and Doug MacEachern spent valuable time writing this book considering the breadth of their subject and the depth they devote to it. The only downside to the book is that it's kind of hard to explain all of the API functionality without assuming a minimum level of competence from the audience. For that reason, this book might be a bit intimidating to novice programmers, but it really rewards you if you put time into it and tinker with things.
The book also works well as a source of ideas and inspiration for when you have to write your own server modules, and I'd recommend it if you want to customize your Apache server or speed up your Perl CGI programs. --Doug Beaver