With ssh key pairs you can easier login to your servers.
To generate an ssh key pair you´ll need to run the following line in your terminal:
ssh-keygen -t dsa
It will ask you for location and pass phrase. You should accept the default location (~/.ssh/id_dsa.pub). For the pass phrase I usually just press return. Then the private key will have a blank pass phrase and you can login to your servers without a password. Comfort vs. security. Your choice.
After this you need to upload the public key to the server.
scp ~/.ssh/id_dsa.pub email@example.com:
Finally login to the server and append the public key to authorized keys:
mkdir .ssh # if it's not already there
cat id_dsa.pub >> .ssh/authorized_keys
rm id_dsa.pub # cleanup
Make sure that the .ssh folder and the authorized_keys have the right permissions:
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
After this, you should be able to login to the server and use scp without having to enter a password.
If you login or copy files to your servers a lot, you can setup an alias in ~/.ssh/config (on your local machine):