While there are plenty of more comprehensive lists out there, there are a few tools I use for web development on a daily basis that are worth talking about.
Some favorite features
- Easily print messages to the Firebug console.
- View (and even modify) HTML and CSS in a nice structured way.
- View network activity and page speed using the Net panel. You can get more page speed information using YSlow or PageSpeed.
excellent guide on setting it up.
- Easily clear domain, url, & session cookies for the current page.
- Turn styles on and off.
- Automatically populate HTML form fields.
- Lots of information about how elements are rendering on the page.
Iconico for picking colors from the screen. Also handy as a general purpose screen-zoom tool.
I'm sure people out there have their own favorite tools and I'd love to hear about them.