FlashTracer

If you're doing Flash/Flex development, FlashTracer is a great Firefox plugin. It simply monitors your Flash log file and pumps its content to the Firefox sidebar. Very simple, but useful. The only problem I've had with it has been on my MacBook. But I got it to work. Here's how.

From the command line...
cd ~/Library/Preferences/Macromedia/"Flash Player"
mkdir Logs
cd Logs
touch flashlog.txt

Open up FlashTracer and click on Options. In the Select Output File enter Macintosh HD:Users::Library:Preferences:Macromedia:Flash Player:Logs:flashlog.txt
Obviously replace with your username (short name). Restart Firefox, and it should work!

Oh yeah, obviously you need to have the debug version of the Flash Player installed...