Useful nohupI just learned about the nohup unix command, which has to be one of the most useful things ever. If you log in to a remote terminal and start a process, it dies when you close the terminal. Prepend "nohup" to your command and it will run long after the invoking window has gone away. Very useful for day-long number crunches when you want to, say, disconnect your laptop from the internet.
A sidenote, à la this previous conversation about dirty unix commands: While looking for nohup, I found an FAQ that includes questions like "How do I keep track of people who are fingering me?".