A standard way of dealing with a system crash / freeze
If force-quitting doesn't work you have a few options:


Sit it out and wait for the Mac to churn through whatever it is stuck on (this doesn't always work, but I've had beachballs go away over time).
Trying opening Activity Viewer and see if you can kill the process there. Same caveat as above.
Force-shutdown the Mac by holding the power button for seven seconds. This always works.


The relationship between Mac OS X and the Unix underpinnings aren't the same as they are between X window/GNOME and the kernel. It isn't nearly as open, so there is really no messing with the kernel near as I can tell in Mac OS X. I usually go the route I mentioned above and as long as I maintain the system properly and regularly I always seem to get back on my feet without any problems.