A quicker way (than this) to set up a password-less login to a server via SSH:
ssh-keygen -t rsa
(When prompted for a password, leave it blank). Then:
cat ~/.ssh/id_rsa.pub | ssh username@hostname 'cat >> .ssh/authorized_keys'
It should be noted that the first step is needed only the first time. Then you can repeat the second command for every other server.