Processes using all resources

[Jonas Norlander]

What do you do when a program is running wild and using all the
resources and you can't use the computer to kill the process? It
happened for me when i left the computer for a couple hours with
firefox running with some flash pages. When i got back the harddisk
was trashing (I think flash crashed and started to use all my memory)
and the GUI almost unresponsive, if i moved the mouse, two minutes
later the mouse pointer moved and open a console, running top to see
what process using all the resources was out of the question.

So what can one do in that case? And don't the kernel have a function
that should kill processes using to much resources (was reading about
that a couple years ago)?

/ Jonas