General :: Ubuntu - Cheatsheet For Commands To Save System?

I've recently lost my window options, had to somehow manipulate my way to Xchat and ask some people how do I get it back (it was metacity --replace, and after I decided to stop the command and run it in background the X was completely useless so I had to do killall -u user). And that was after the internet connection stopped working for some reason (might've been the ISP).

The thing is, after using linux a long time, I still get the feeling that on dire situations, I don't know the good tricks (stuff like metacity --replace). I feel like a really need like a "rescue" cheatsheet for things like: how to save the X no matter what without pressing reset how to reset the system to "normal state" how to connect to the internet through the command line how to monitor what the X is doing (using ubuntu linux 10.04 btw)