As a web developer, I'm constantly using Firebug, but when it comes to testing in IE it's a nightmare if there's any bugs. Firebug does provide a 'lite' version, but you have to have in it in every page you want to debug. Well, not anymore.

Firebug 1.0 beta for Firefox was released this month, and oh my, the Swiss Army knife of the browsers just got wings - and there's even support (via a Firebug Lite) for IE, Safari and Opera.