SSHP - Let's Pablo memorize your SSH credentials.

gem install sshp

To save an alias without hostname:

sshp-alias u -i ~/keys/my_key.pem -l ubuntu

Then

sshp u hostname.com

To save an alias with hostname:

sshp-alias u -i ~/keys/my_key.pem -l ubuntu hostname.com

Then

sshp u

All aliases will be saved at ~/.sshp.

Remember that you can also use ssh_config for many cases in place of sshp.

# ~/.ssh/config
Host u
    HostName hostname.com
    User ubuntu
    IdentityFile ~/keys/my_key.pem

Then

ssh u

Have a look at "Simplify Your Life With an SSH Config File" it is a well detailed post about ssh_config.

The difference between sshp vs ssh_config is that using sshp you can save the aliases without Host and HostName, you can save only the credentianls, which is usefull when you have multiple servers/hosts using the same credentianls i.e. sshp u host-a, sshp u host-b etc.