Firebug is the Dog’s Bollocks, In fact I’m finding the trinity of Firebug , Aptana and JSunit a truly fantastic setup for developing robust browser based applications. I just read Justin Palmer’s tutorial on the logging capabilities of Firebug. Really good info, well presented. excellent signal to noise ratio.
Although I already knew most of the stuff covered, as I had been a beta tester of Firebug 0.4, I had missed the trace() function and the fact that the standard log() functions support jQuery/Prototype $functions so you can use the following incredibly useful pattern to inspect the html of the object you are manipulating.
Read the article and write better code.