Something that I find very useful is the screen command.

It comes in handy when you want to SSH back to the same session on a box. For example if you're running some kind of client eg an IRC client, usually when you close the SSH session you won't be able to go back to your IRC screen. The program screen solves this. Here's an example:
Code:
screen -t irc Bitchx
Now you're running Bitchx on a new terminal. To get back to your original terminal you press ^ad (Control+A, then D). The D stands for Detach.
You can now close your SSH session while the Bitchx client still runs. When you SSH in again, run the command
Code:
screen -r
And voila you're looking at the same Bitchx client you left running before.