This is a filesystem client based on the SSH File Transfer Protocol. Since most SSH servers already support this protocol it is very easy to set up: i.e. on the server side there’s nothing to do. On the client side mounting the filesystem is as easy as logging into the server with ssh.
SSHFS is the coolest thing in the universe, and it’s easy to install in Ubuntu.
And by “coolest thing in the universe,” I mean totally sweet.