commandlinefu.com is the place to record those command-line gems that you return to again and again.
You can sign-in using OpenID credentials, or register a traditional username and password.
Subscribe to the feed for:
Useful when you're trying to unmount a volume and other sticky situations where a rogue process is annoying the hell out of you.
Substitute nano with your favorite editor, of course.
To make it even more practical, make sure you can login to the ssh server using a keypair.