Do you remember Jetpack?
It is the Mozilla Labs project that makes the add-on building process easier, mixing elements of HTML, CSS and JavaScript.  Mozilla has released an awesome Jetpack Gallery, which serves as a community for Jetpack developers and add-on users.

One thing is for sure, with the correctly equipped Firefox browser, you too can become a better web designer or developer. How so? Well, Firefox has some really great tools for both of these jobs. Finding the one that doe the best job, is another job all on it’s own.
Firefox has a lot of web development add-ons you can use, however these are the best of the best at what they do.

Console² – Console² (pronounced Console Squared [...]

The URL Lister add-on for Firefox gives you the ability to grab all the open tabs you have, and collect them as a series of links, formatted in three different formats, so that they can be copied easily.

To use, all you need to do is right-click on one of the tabs, and select URL Lister.  Next, you will see a box (like the one above) that will give you URLs (one per line) for each tab you have [...]

Ever wanted to write your own Firefox extension, but thought the process was too drawn out or difficult to do?  Jetpack is looking to use open Web technologies to enhance the browser.  The idea here is that if you can make a web page, you will be able to build an add-on for Firefox.
This video does a great job at giving you a basic walk-though of what Jetpack development looks like thus far:

Mozilla Labs Jetpack – Intro & Tutorial from [...]

One of those pesky things that bug me is when somebody writes a link in that I want to click, but there is no HTML code included to make it into a click-able link.  Thankfully several add-ons for Firefox have figured out how to turn URLs and e-mail addresses not marked up as a link into things I can click on.
There are eight add-ons for Firefox that do this job very well.  The only problem is that there is [...]

When web development and design is mentioned, everybody’s top Firefox extension is the Web Developer toolbar. There are a few other choices out there for design and coding tools that you might have not of seen before.
View Source Chart – This extension does one job and does it well. It draws colored boxes around different source codes to help you read the information better. Instead of black and white confusing stuff – it’s all colored man. [...]

Finding yourself in a bind with your web site design? Maybe you just can’t get your CSS to level out with your HTML? If you find yourself in these shoes we talk about, you might need to pick up the Total Validator extension for Firefox.
Perform multiple validations and take screen shots in one go. This 5-in-1 validator works with external, internal, or local web pages using the Total Validator service or local copy of the Pro desktop [...]

I hate it when a PDF opens up inside of my browser, no matter which one I am using. It wastes my time and I would rather not have Adobe get it’s mitts all over my beautiful Firefox interface. Now you can either poke it back with a stick – which is not the easiest thing to do Online – or you can pick up the PDF Download extension fore Firefox. This extension allows to choose if [...]

True, some Web sites do not give you a really nice text editor to work with. Some of the text input forms on the Web are down-right ugly at times. Don’t you wish you could just take your own HTML editor to any Online form so your written words might look a little nicer? That is what Xinha Here! allows you to do. Think of it as icing on the cake when it comes to editing [...]

There hasn’t been anything new added to viewing a Web site’s source code in some time now. Personally I don’t like the viewer that comes built in with Firefox. I would rather use my own note program to view a Web site’s HTML code. What am I to do? I picked up the ViewSourceWith Firefox extension.
[Learn More About ViewSourceWith!]