if you do not already have a key pair
$ ssh-keygen -t dsa

send your public key to each host you ssh into
$ cat ~/.ssh/id_dsa.pub | ssh you@host 'cat - >> ~/.ssh/authorized_keys2'

now you can use ssh-agent and ssh-add to facilitate a "single signon" situation.

useful if you're ssh'ing into a bunch of machines all day.

google ssh-agent for distribution-specific details.