Trying to kill a program stuck on an infinite Rainbow Wheel wait, I'm not sure what the process name is so ps -eaf and kill won't help me. Fortunately, OSX has a task manager GUI like Windows, it's just hidden like everything else on a mac. To get the GUI task manager, just hold down option, command and escape at the same time.
From here:
http://forums.macrumors.com/showthread.php?t=100694
