If you are still using Firefox just for Firebug, I bet you will switch to Chrome after watching this video.  I used to stick with Firefox while developing since Firebug was so good at what it did, but Google is doing great things with their dev tools.  The following talk is from Google I/O 2011 featuring Paul Irish and Pavel Feldman.  The talk mostly covers new features, but you can take a look at their docs site for all the features.

The video clocks in at just over 40 mins but it is well worth the time.