One of the biggest 'ah-ha' moments I had with SSH was that I could create my own hosts with certain properties. For example, if I wanted a backup server with a special user and key I could add it to my ~/.ssh/config file

  Host backup-server
      HostName backup.example.com
      User backup
      IdentityFile ~/.ssh/backup_dsa

Then just have a shell script run

  $ ssh backup-server

It ended up working really well.

Also, control sockets.