Although I use Safari for much of my browsing, I still use Firefox for a number of things. I find that playing Shartak with anything other than Firefox is painful because the Greasemonkey scripts for Shartak make it so much easier to find out where my character is. I also use Firefox whenever I need to dig into some HTML/CSS problems – the Web Developer add-on makes it easy to find out which styles are being applied to an element.
Here is a list of some of the Firefox add-ons that I’ve come across and would recommend.