Zen, firebug is the best! Fuck Venkman. With the Web Developer and Firebug extensions, you can do everything you need for website development. I use it to debug Ajax shit. I wouldn't download FF 3.0 beta on my development machines because firebug wasn't ready for 3.0 beta. 3.0 seems to be much better with Ajax auto-suggest controls (at least the ones I write). The html textarea command looks and works nicer in 3.0.