Useful SSH usage

This post has a command that is useful about running SQL statement.
https://gist.github.com/scy/6781836
The command is:

mysql -e 'SHOW DATABASES;' -h 127.0.0.1 | ssh -L 3306:localhost:3306 remotehost cat

This post is good too about ssh without password instead of using rsa key:
http://serverfault.com/questions/241588/how-to-automate-ssh-login-with-password

ssh-keygen -t rsa -b 2048

ssh-copy-id id@server