One of my favorite tools just went one point oh! - An oh what an upgrade! Firebug went from totally cool, to insanely great - if you haven't upgaded already then hurry up, if you haven't installed it, the do it - you won't regret it! It has even obsoleted a couple of other plugins as you can now do inline editing of CSS and lots of other cool stuff! For users of lesser browsers, there is even a lite version so they can develop with Firebug and use all the cool features on their development site that we can use on any site! Oh... did it forget to mention it is free ?