Jaisen Mathai has a helpful hint for those that do any offline work with PHP on their own development systems - how to mirror the PHP manual on a local web server.
In addition to [a local copy of your source] being faster to develop, it lets you work without needing to be connected to the Internet. But what about the tools you use while developing? If you're a PHP developer then the manual at php.net is an invaluable tool. It only make sense to have it available for when you're not online.
His example follows the official mirroring part of the PHP.net website and uses a slightly modified rsync command to fetch the manual information from the php.net site and drops it in a location locally. He throws in an Apache configuration too for a simple VirtualHost to get it up and running.