If you're like me, you use Firebug a lot, like, all day long. Long gone are the days of resorting to alerts. The worst I'll fall back to is using the YUI logger for IE.
I've recently been having a lot of issues using Firefox 3, and Firebug. Firefox 3 has been pretty consistent at crashing a few times throughout the day. Firebug 1.2 has recently been causing me more and more troubles, to the point where I can't get it to not stop at breakpoints that I've removed, or it stops at my breakpoint, but doesn't let me play it through or debug, or remove the breakpoint, because it doesn't show up as being registered.
I'm sure these are hiccups with the new version of Firefox 3, but it is pretty disruptive to me as I'm developing. I reverted back to Firefox 2 and an older version of Firebug until they get this sorted out, which I'm sure will be soon. For anyone looking, you can find old versions of Firefox on FileHippo, and past versions of Firebug from the normal download site.