I guess this tip is known by a lot of developers but three people asked me how to do it, so killing processes seems a bit harder to discover for newbies.
Question: I started my program in NetBeans and now I want to kill it. How do I do that?
Answer: Go to Runtime tab (or press Ctrl-5 to invoke it), choose Processes, right-click on the process you want to stop and choose terminate process. Rest in pieces.
Death to all processes
I wish some things in life were as easy as killing processes in NetBeans :)