When developing AIR applications under flexbuilder you may get a situation where the app is stuck in an unresponsive state and refuses to quit itself.
To kill it quickly on a Mac you can do the following from a terminal:
ps -A | grep adl
That will return a line that looks something like this
18132 ?? S 0:22.97 /Users/joshbloom/Applications/flexb_183522/Adobe Flex Builder 3/sdks/3.0.0/bin/adl -runtime /Users/joshbloom/Appl
18148 p1 S+ 0:00.00 grep adl
The number at the beginning of the first line first line indicates the process ID of your unresponsive AIR app.
To kill it you would run this command:
kill -9 18132
Be careful what number you put into the kill command, it will happily kill anything you tell it to. If you make a mistake you may have killed your window manager, your instant messenger or even something important like your twitter client.