As a PHP developer there are a hoard of Mozilla Firefox add-ons that will not only make your life easier, but will make you a better developer.
These are the list of add-ons that are installed by default in my Firefox Browser.
Web Developer – the first developer add-on I ever installed and one that I can’t live without. Manipulate everything from styling to sessions using this tool.
Tamper Data – extremely useful tool for viewing/modifying your http requests to see what is being sent/received each time a page is loaded.
PHP Developer Toolbar – tired of opening php.net each time you want to search a function. Use this handy toolbar to save time and frustration.