If you are using Firefox for your APEX development you may want to check out my list of add-ons I’m currently using for the web development. If you have any useful add-ons you are using, drop me a note!
FireBug
If you are doing JavaScript programming than this add-on is a MUST. Because it provides a JavaScript debugger and that’s really sometimes necessary, especially if you just started writing JavaScript as I do.
Download it at https://addons.mozilla.org/firefox/1843/
Live HTTP Headers
With this addon you see what’s going on in the background, what data is transfered from and what is coming back from the server.
Download it at https://addons.mozilla.org/firefox/3829/
View cookies
It adds a tab to the Page Info dialog box, which shows the cookies of the current web-page.
Download it at https://addons.mozilla.org/firefox/315/
Web Developer
Just downloaded and installed this add-on. Very feature rich, lot of options, …
Will see how useful it is during development.
Download it at https://addons.mozilla.org/firefox/60/
Not (directly) related to development, but I strongly recommend the AdBlock and ForecastFox plugins for Firefox.
Write Area is really good for editing HTML blocks. If you have a static HTML region and just want to smash out some formatted text, right click on the source text area, open in Write Area, use the rich text editor to make it look all pretty.