I use Firebug to edit a site's CSS in real-time whenever I'm having trouble with a skin. ColorZilla is what I use to grab colors to play around with when I'm making skins. I have FoxyProxy installed but I'm not sure what it's for, don't use it and don't remember adding it. I have Animated Matrix for my Appearance. It was distracting at first but I forced myself to like it. I had GreaseMonkey but I uninstalled it because I couldn't figure out how to uninstall this.