My favorite Firefox extension these days is the Web Developer toolbar.

I stumbled across it last week when I was looking for a way to clear the http authentication without having to close and restart my browser. The toolbar has a menu for that, plus dozens of more features.

The toolbar is great for analyzing web pages, particularly if you’re trying to figure out how a particular page is structured. The toolbar makes it easy to see all the relevant information about positioning, images, tables, etc. Definitely a fun tool to add to your firefox.