The new version of Firebug is finally released !!!
This is an awesome tool to debug and profile javascript. It has a lot of new features
compare to the previous releases.
Here is a great video of Joe Hewitt (Firebug’s author) about those new features :
http://yuiblog.com/blog/2007/01/26/video-hewitt-firebug/
I also recommend Firebug Lite that provides the console logger for other Browsers