While looking around at web developer hints and tips, you'll often read of people's love for Firefox and Firebug as if that's the pinnacle of debugging. Well, they're wrong.
Firebug has always seemed slow, buggy and not exactly easy to navigate. An example of this is that while writing this post, I examined Firebug to check that I wasn't missing something and while Firebug does have some of the features I describe below, they aren't located on the Script tab.
This has been especially helpful when coding for Twitterfall. Recently, we've been focusing on reimplementing areas of the code to make it more efficient and have a lower footprint.
Sometimes, you just need to be able to test whether writing a function a specific way will give you the output you want. On these occasions it's so nice to be able to open the Inspector and just start typing.