If you’ve been waiting to try out Firebug for any reason, wait no longer. Skip right past the current release and install the the new 1.0 Beta.
I can describe this new version in one word: Amazing. Firebug will make debugging your web app a joy. No matter if the problem is in the markup, script, CSS, or HTTP request/response, Firebug will help you find it. You’ll actually want to have bugs just so you can use it. Great to see it’s going to stay open source too.