SSH without password (keys)

Using keys to connect to a server without a password  

In this example I'm connecting from a local machine to a remote server.

On your local machine run:
ssh-keygen -t rsa

Do NOT enter a passphrase

On the server, create the following if it doesn't exist:
~/.ssh/authorized_keys2

Now copy your local key to the server:
cat ~/.ssh/id_rsa.pub | ssh remote-server "cat >> .ssh/authorized_keys2"